From abc39feca8eaa328df042559ed4911fcb13b4276 Mon Sep 17 00:00:00 2001
From: dsm <41967334+dsm@users.noreply.github.com>
Date: Tue, 23 Jul 2024 12:54:48 +0300
Subject: [PATCH] Properties migrated to QList

---
 qucs/components/DLS_nto1.cpp              |   2 +-
 qucs/components/ac_sim.cpp                |  21 +--
 qucs/components/bjt.cpp                   |   4 +-
 qucs/components/component.cpp             | 131 +++++++------
 qucs/components/component.h               |   5 +-
 qucs/components/componentdialog.cpp       | 214 +++++++++++-----------
 qucs/components/dff_SR.cpp                |   3 +-
 qucs/components/digi_source.cpp           |  20 +-
 qucs/components/ecvs.cpp                  |   2 +-
 qucs/components/eqndefined.cpp            |  21 +--
 qucs/components/equation.cpp              |   4 +-
 qucs/components/ifile.cpp                 |   7 +-
 qucs/components/libcomp.cpp               |  32 ++--
 qucs/components/mosfet.cpp                |  17 +-
 qucs/components/mosfet_sub.cpp            |  15 +-
 qucs/components/msvia.cpp                 |   2 +-
 qucs/components/mutualx.cpp               |   9 +-
 qucs/components/opt_sim.cpp               |  92 +++++-----
 qucs/components/optimizedialog.cpp        |  53 +++---
 qucs/components/param_sweep.cpp           |  22 +--
 qucs/components/potentiometer.cpp         |   2 +-
 qucs/components/rfedd.cpp                 |  24 ++-
 qucs/components/rfedd2p.cpp               |  22 +--
 qucs/components/sp_sim.cpp                |  21 +--
 qucs/components/sparamfile.cpp            |  12 +-
 qucs/components/spicedialog.cpp           |  32 ++--
 qucs/components/subcircuit.cpp            |  23 ++-
 qucs/components/switch.cpp                |  10 +-
 qucs/components/tr_sim.cpp                |  21 +--
 qucs/components/vfile.cpp                 |   7 +-
 qucs/components/vhdlfile.cpp              |  26 +--
 qucs/dialogs/changedialog.cpp             |   4 +-
 qucs/dialogs/fillfromspicedialog.cpp      |   2 +-
 qucs/extsimkernels/spicelibcompdialog.cpp |  30 +--
 qucs/spicecomponents/sp_nutmeg.cpp        |  10 +-
 35 files changed, 449 insertions(+), 473 deletions(-)

diff --git a/qucs/components/DLS_nto1.cpp b/qucs/components/DLS_nto1.cpp
index a745f781..044c85a6 100644
--- a/qucs/components/DLS_nto1.cpp
+++ b/qucs/components/DLS_nto1.cpp
@@ -31,7 +31,7 @@ DLS_nto1::DLS_nto1()
 Component * DLS_nto1::newOne()
 {
   DLS_nto1 * p = new DLS_nto1();
-  p->Props.front()->Value = Props.front()->Value; 
+  p->Props.front()->Value = Props.front()->Value;
   p->recreate(0); 
   return p;
 }
diff --git a/qucs/components/ac_sim.cpp b/qucs/components/ac_sim.cpp
index a9486ae6..a3a8b8df 100644
--- a/qucs/components/ac_sim.cpp
+++ b/qucs/components/ac_sim.cpp
@@ -64,21 +64,18 @@ Element* AC_Sim::info(QString& Name, char* &BitmapFile, bool getNewOne)
 
 void AC_Sim::recreate(Schematic*)
 {
-  Property *pp = Props.first();
-  if((pp->Value == "list") || (pp->Value == "const")) {
+  if((Props.at(0)->Value == "list") || (Props.at(0)->Value == "const")) {
     // Call them "Symbol" to omit them in the netlist.
-    pp = Props.next();
-    pp->Name = "Symbol";
-    pp->display = false;
-    pp = Props.next();
-    pp->Name = "Symbol";
-    pp->display = false;
-    Props.next()->Name = "Values";
+    Props.at(1)->Name = "Symbol";
+    Props.at(1)->display = false;
+    Props.at(2)->Name = "Symbol";
+    Props.at(2)->display = false;
+    Props.at(3)->Name = "Values";
   }
   else {
-    Props.next()->Name = "Start";
-    Props.next()->Name = "Stop";
-    Props.next()->Name = "Points";
+    Props.at(1)->Name = "Start";
+    Props.at(2)->Name = "Stop";
+    Props.at(3)->Name = "Points";
   }
 }
 
diff --git a/qucs/components/bjt.cpp b/qucs/components/bjt.cpp
index 3c9d7f98..79550791 100644
--- a/qucs/components/bjt.cpp
+++ b/qucs/components/bjt.cpp
@@ -85,7 +85,7 @@ Element* BJT::info_pnp(QString& Name, char* &BitmapFile, bool getNewOne)
 
   if(getNewOne) {
     BJT* p = new BJT();
-    p->Props.front()->Value = "pnp";
+    p->Props.at(0)->Value = "pnp";
     p->recreate(0);
     return p;
   }
@@ -130,7 +130,7 @@ QString BJT::netlist()
   s += " "+Ports.at(1)->Connection->Name;  // connect substrate to collector
 
   // output all properties
-  for(Property *p2 = Props.first(); p2 != nullptr; p2 = Props.next())
+  for(const auto& p2 : Props)
     s += " "+p2->Name+"=\""+p2->Value+"\"";
 
   return s + '\n';
diff --git a/qucs/components/component.cpp b/qucs/components/component.cpp
index 0d23feed..16fb65fd 100644
--- a/qucs/components/component.cpp
+++ b/qucs/components/component.cpp
@@ -64,7 +64,6 @@ Component::Component() {
     tx = 0;
     ty = 0;
 
-    Props.setAutoDelete(true);
 
     containingSchematic = NULL;
 }
@@ -549,7 +548,7 @@ void Component::rotate() {
         dx = metrics.boundingRect(Name).width();
         dy = metrics.lineSpacing();
     }
-    for (Property *pp = Props.first(); pp != 0; pp = Props.next())
+    for (Property *pp : Props)
         if (pp->display) {
             // get width of text
             tmp = metrics.boundingRect(pp->Name + "=" + pp->Value).width();
@@ -631,7 +630,7 @@ void Component::mirrorX() {
     int dy = 0;
     if (showName)
         dy = metrics.lineSpacing();   // for "Name"
-    for (Property *pp = Props.first(); pp != nullptr; pp = Props.next())
+    for (Property *pp : Props)
         if (pp->display) dy += metrics.lineSpacing();
     if ((tx > x1) && (tx < x2)) ty = -ty - dy;     // mirror text position
     else ty = y1 + ty + y2;
@@ -699,7 +698,7 @@ void Component::mirrorY() {
     int dx = 0;
     if (showName)
         dx = metrics.boundingRect(Name).width();
-    for (Property *pp = Props.first(); pp != 0; pp = Props.next())
+    for (Property *pp : Props)
         if (pp->display) {
             // get width of text
             tmp = metrics.boundingRect(pp->Name + "=" + pp->Value).width();
@@ -723,7 +722,7 @@ QString Component::netlist() {
         s += " " + p1->Connection->Name;   // node names
 
     // output all properties
-    for (Property *p2 = Props.first(); p2 != nullptr; p2 = Props.next())
+    for (Property *p2 : Props)
         if (p2->Name != "Symbol")
             s += " " + p2->Name + "=\"" + p2->Value + "\"";
 
@@ -941,7 +940,7 @@ QString Component::save() {
     s += " " + QString::number(rotated);
 
     // write all properties
-    for (Property *p1 = Props.first(); p1 != 0; p1 = Props.next()) {
+    for (Property *p1 : Props) {
         QString val = p1->Value; // enable newline in properties
         val.replace("\n", "\\n");
         val.replace("\"", "''");
@@ -1013,7 +1012,7 @@ bool Component::load(const QString &_s) {
     tx = ttx;
     ty = tty; // restore text position (was changed by rotate/mirror)
 
-    unsigned int z = 0, counts = s.count('"');
+    unsigned int counts = s.count('"');
     if (Model == "Sub")
         tmp = 2;   // first property (File) already exists
     else if (Model == "Lib")
@@ -1032,8 +1031,8 @@ bool Component::load(const QString &_s) {
         Props.append(new Property("p", "", true, " "));
 
     // load all properties
-    Property *p1;
-    for (p1 = Props.first(); p1 != 0; p1 = Props.next()) {
+    unsigned int z = 0;
+    for (auto p1 = Props.begin(); p1 != Props.end(); ++p1) {
         z++;
         n = s.section('"', z, z);    // property value
         n.replace("\\n", "\n");
@@ -1043,49 +1042,58 @@ bool Component::load(const QString &_s) {
 
         // not all properties have to be mentioned (backward compatible)
         if (z > counts) {
-            if (p1->Description.isEmpty())
-                Props.remove();    // remove if allocated in vain
+          if ((*p1)->Description.isEmpty())
+                Props.clear();    // remove if allocated in vain
 
             if (Model == "Diode") {
                 if (counts < 56) {  // backward compatible
                     counts >>= 1;
-                    p1 = Props.at(counts - 1);
-                    for (; p1 != 0; p1 = Props.current()) {
+                    p1 = Props.begin();
+                    for(int i = 0; i < int(counts)-1 && p1 != Props.end(); ++i)
+                      ++p1;
+                    for (; p1 != 0; p1 = Props.begin()) {
                         if (counts-- < 19)
                             break;
-
-                        n = Props.prev()->Value;
-                        p1->Value = n;
+                        auto p1prev = p1;
+                        --p1prev;
+                        (*p1)->Value = n;
+                        --p1;
                     }
 
-                    p1 = Props.at(17);
-                    p1->Value = Props.at(11)->Value;
-                    Props.current()->Value = "0";
+                    Props.at(17)->Value = Props.at(11)->Value;
+                    (*p1)->Value = "0";
                 }
             } else if (Model == "AND" || Model == "NAND" || Model == "NOR" ||
                        Model == "OR" || Model == "XNOR" || Model == "XOR") {
                 if (counts < 10) {   // backward compatible
                     counts >>= 1;
-                    p1 = Props.at(counts);
-                    for (; p1 != 0; p1 = Props.current()) {
+                    p1 = Props.begin();
+                    for(int i = 0; i < int(counts) && p1 != Props.end(); ++i)
+                      ++p1;
+                    for (; p1 != Props.begin();) {
                         if (counts-- < 4)
                             break;
-                        n = Props.prev()->Value;
-                        p1->Value = n;
+                        auto p1prev = p1;
+                        --p1prev;
+                        (*p1)->Value = (*p1prev)->Value;
+                        --p1;
                     }
-                    Props.current()->Value = "10";
+                    (*p1)->Value = "10";
                 }
             } else if (Model == "Buf" || Model == "Inv") {
                 if (counts < 8) {   // backward compatible
                     counts >>= 1;
-                    p1 = Props.at(counts);
-                    for (; p1 != 0; p1 = Props.current()) {
+                  for(int i = 0; i < int(counts) && p1 != Props.end(); ++i)
+                    ++p1;
+                  for(; p1 != Props.begin(); ) {
                         if (counts-- < 3)
                             break;
-                        n = Props.prev()->Value;
-                        p1->Value = n;
+                        auto p1prev = p1;
+                        --p1prev;
+                        (*p1)->Value = (*p1prev)->Value;
+                        --p1;
                     }
-                    Props.current()->Value = "10";
+                    (*p1)->Value = "10";
                 }
             }
 
@@ -1094,13 +1102,14 @@ bool Component::load(const QString &_s) {
 
         // for equations
         if (Model != "EDD" && Model != "RFEDD" && Model != "RFEDD2P")
-            if (p1->Description.isEmpty() || p1->Description == "Expression") {  // unknown number of properties ?
-                p1->Name = n.section('=', 0, 0);
+            if ((*p1)->Description.isEmpty() || (*p1)->Description == "Expression") {  // unknown number of properties ?
+                (*p1)->Name = n.section('=', 0, 0);
                 n = n.section('=', 1);
                 // allocate memory for a new property (e.g. for equations)
-                if (Props.count() < (counts >> 1)) {
-                    Props.insert(z >> 1, new Property("y", "1", true));
-                    Props.prev();
+                if (Props.size() < (counts >> 1)) {
+                    auto p1next = p1;
+                    ++p1next;
+                    Props.insert(p1next, new Property("y", "1", true));
                 }
             }
         if (z == 6)
@@ -1109,10 +1118,10 @@ bool Component::load(const QString &_s) {
                     Props.back()->Value = n;
                     return true;
                 }
-        p1->Value = n;
+        (*p1)->Value = n;
 
         n = s.section('"', z, z);    // display
-        p1->display = (n.at(1) == '1');
+        (*p1)->display = (n.at(1) == '1');
     }
 
     return true;
@@ -1181,30 +1190,30 @@ int Component::analyseLine(const QString &Row, int numProps) {
         if (Name.isEmpty()) Name = "SUB";
 
         i1 = 1;
-        Property *pp = Props.at(numProps - 1);
+        auto pp = Props.begin();
+        for(int i = 0; i < (numProps) && pp != Props.end(); ++i)
+          ++pp;
         for (;;) {
             s = Row.section('"', i1, i1);
             if (s.isEmpty()) break;
 
-            pp = Props.next();
-            if (pp == 0) {
-                pp = new Property();
-                Props.append(pp);
-
-                pp->display = (s.at(0) == '1');
-                pp->Value = s.section('=', 2, 2);
+            pp++;
+            if (pp == Props.end()) {
+                Props.append(new Property());
+                pp = --Props.end();
+                (*pp)->display = (s.at(0) == '1');
+                (*pp)->Value = s.section('=', 2, 2);
             }
 
-            pp->Name = s.section('=', 1, 1);
-            pp->Description = s.section('=', 3, 3);
-            if (pp->Description.isEmpty())
-                pp->Description = " ";
+            (*pp)->Name = s.section('=', 1, 1);
+            (*pp)->Description = s.section('=', 3, 3);
+            if ((*pp)->Description.isEmpty())
+                (*pp)->Description = " ";
 
             i1 += 2;
         }
 
-        while (pp != Props.last())
-            Props.remove();
+        Props.erase(pp, Props.end());
         return 0;   // do not count IDs
     } else if (s == "Arrow") {
         if (!getIntegers(Row, &i1, &i2, &i3, &i4, &i5, &i6)) return -1;
@@ -1402,11 +1411,14 @@ bool Component::getBrush(const QString &s, QBrush &Brush, int i) {
 
 // ---------------------------------------------------------------------
 Property *Component::getProperty(const QString &name) {
-    for (Property *pp = Props.first(); pp != 0; pp = Props.next())
-        if (pp->Name == name) {
-            return pp;
-        }
-    return NULL;
+    for(auto pp = Props.begin(); pp != Props.end(); ++pp) {
+      if((*pp)->Name == name) {
+        return *pp;
+      }
+    }
+    Props.append( new Property());
+    Props.back()->Name = name;
+    return Props.back();
 }
 
 // ---------------------------------------------------------------------
@@ -1511,12 +1523,9 @@ QString GateComponent::netlist() {
         s += " " + pp->Connection->Name;   // node names
 
     // output all properties
-    Property *p = Props.at(1);
-    s += " " + p->Name + "=\"" + p->Value + "\"";
-    p = Props.next();
-    s += " " + p->Name + "=\"" + p->Value + "\"";
-    p = Props.next();
-    s += " " + p->Name + "=\"" + p->Value + "\"\n";
+    s += " " + Props.at(1)->Name + "=\"" + Props.at(1)->Value + "\"";
+    s += " " + Props.at(2)->Name + "=\"" + Props.at(2)->Value + "\"";
+    s += " " + Props.at(3)->Name + "=\"" + Props.at(3)->Value + "\"\n";
     return s;
 }
 
diff --git a/qucs/components/component.h b/qucs/components/component.h
index da1e7f2c..9e150d0f 100644
--- a/qucs/components/component.h
+++ b/qucs/components/component.h
@@ -23,7 +23,8 @@
 // builds fail without explicit QObject inclusion
 #include <QObject>
 #include "extsimkernels/spicecompat.h"
-#include "qt3_compat/qt_compat.h"
+
+#include <QList>
 
 #include "element.h"
 
@@ -90,7 +91,7 @@ public:
   QList<qucs::Ellips *>     Ellipses;
   QList<Port *>     Ports;
   QList<Text *>     Texts;
-  Q3PtrList<Property> Props;
+  QList<Property*> Props;
 
   #define COMP_IS_OPEN    0
   #define COMP_IS_ACTIVE  1
diff --git a/qucs/components/componentdialog.cpp b/qucs/components/componentdialog.cpp
index 42ddee3a..a3549d93 100644
--- a/qucs/components/componentdialog.cpp
+++ b/qucs/components/componentdialog.cpp
@@ -75,7 +75,9 @@ ComponentDialog::ComponentDialog(Component *c, Schematic *d)
   checkSim  = 0;  comboSim  = 0;  comboType  = 0;  checkParam = 0;
   editStart = 0;  editStop = 0;  editNumber = 0;
   
-  Property *pp = 0; // last property shown elsewhere outside the properties table, not to put in TableView
+  // last property shown elsewhere outside the properties table, not to put in TableView
+  auto pp = Comp->Props.begin();
+
   // ...........................................................
   // if simulation component: .TR, .AC, .SW, (.SP ?)
   if((Comp->Model[0] == '.') &&
@@ -197,33 +199,35 @@ ComponentDialog::ComponentDialog(Component *c, Schematic *d)
           if(pc->Model[0] == '.')
             comboSim->insertItem(comboSim->count(), pc->Name);
       }
-      qDebug() << "[]" << Comp->Props.first()->Value;
+      qDebug() << "[]" << (*pp)->Value;
       // set selected simulations in combo box to the currently used one
-      int i = comboSim->findText(Comp->Props.first()->Value);
+      int i = comboSim->findText((*pp)->Value);
       if (i != -1) // current simulation is in the available simulations list (normal case)
 	comboSim->setCurrentIndex(i);
       else  // current simulation not in the available simulations list
-	comboSim->setEditText(Comp->Props.first()->Value);
+        comboSim->setEditText((*pp)->Value);
 
-      checkSim->setChecked(Comp->Props.current()->display);
-      s = Comp->Props.next()->Value;
-      checkType->setChecked(Comp->Props.current()->display);
-      editParam->setText(Comp->Props.next()->Value);
-      checkParam->setChecked(Comp->Props.current()->display);
+      checkSim->setChecked((*pp)->display);
+      ++pp;
+      s = (*pp)->Value;
+      checkType->setChecked((*pp)->display);
+      ++pp;
+      editParam->setText((*pp)->Value);
+      checkParam->setChecked((*pp)->display);
     }
     else {
-      s = Comp->Props.first()->Value;
-      checkType->setChecked(Comp->Props.current()->display);
+      s = (*pp)->Value;
+      checkType->setChecked((*pp)->display);
     }
-    pp = Comp->Props.next();
-    editStart->setText(pp->Value);
-    checkStart->setChecked(pp->display);
-    pp = Comp->Props.next();
-    editStop->setText(pp->Value);
-    checkStop->setChecked(pp->display);
-    pp = Comp->Props.next();  // remember last property for ListView
-    editNumber->setText(pp->Value);
-    checkNumber->setChecked(pp->display);
+    ++pp;
+    editStart->setText((*pp)->Value);
+    checkStart->setChecked((*pp)->display);
+    ++pp;
+    editStop->setText((*pp)->Value);
+    checkStop->setChecked((*pp)->display);
+    ++pp;  // remember last property for ListView
+    editNumber->setText((*pp)->Value);
+    checkNumber->setChecked((*pp)->display);
 
     int tNum = 0;
     if(s[0] == 'l') {
@@ -240,7 +244,7 @@ ComponentDialog::ComponentDialog(Component *c, Schematic *d)
     if(tNum > 1) {
       editValues->setText(
 		editNumber->text().mid(1, editNumber->text().length()-2));
-      checkValues->setChecked(Comp->Props.current()->display);
+      checkValues->setChecked((*pp)->display);
       editNumber->setText("2");
     }
     slotNumberChanged(0);
@@ -449,34 +453,34 @@ ComponentDialog::ComponentDialog(Component *c, Schematic *d)
 
   /*! Insert all \a Comp properties into the dialog \a prop list */
   int row=0; // row counter
-  for(Property *p = Comp->Props.at(Comp->Props.find(pp)+1); p != 0; p = Comp->Props.next()) {
+  for(auto p = pp; p != Comp->Props.end(); ++p) {
 
       // do not insert if already on first tab
       // this is the reason it was originally from back to front...
       // the 'pp' is the lasted property stepped over while filling the Swep tab
   //    if(p == pp)
   //      break;
-      if(p->display)
+      if((*p)->display)
         s = tr("yes");
       else
         s = tr("no");
 
       // add Props into TableWidget
-      qDebug() << " Loading Comp->Props :" << p->Name << p->Value << p->display << p->Description ;
+      qDebug() << " Loading Comp->Props :" << (*p)->Name << (*p)->Value << (*p)->display << (*p)->Description ;
 
       prop->setRowCount(prop->rowCount()+1);
 
       QTableWidgetItem *cell;
-      cell = new QTableWidgetItem(p->Name);
+      cell = new QTableWidgetItem((*p)->Name);
       cell->setFlags(cell->flags() ^ Qt::ItemIsEditable);
       prop->setItem(row, 0, cell);
-      cell = new QTableWidgetItem(p->Value);
+      cell = new QTableWidgetItem((*p)->Value);
       cell->setFlags(cell->flags() ^ Qt::ItemIsEditable);
       prop->setItem(row, 1, cell);
       cell = new QTableWidgetItem(s);
       cell->setFlags(cell->flags() ^ Qt::ItemIsEditable);
       prop->setItem(row, 2, cell);
-      cell = new QTableWidgetItem(p->Description);
+      cell = new QTableWidgetItem((*p)->Description);
       cell->setFlags(cell->flags() ^ Qt::ItemIsEditable);
       prop->setItem(row, 3, cell);
 
@@ -541,36 +545,37 @@ void ComponentDialog::updateCompPropsList()
     QString s;
     int row=0; // row counter
     //for(Property *p = Comp->Props.first(); p != 0; p = Comp->Props.next()) {
-    for(Property *p = Comp->Props.at(last_prop); p != 0; p = Comp->Props.next()) {
+    auto &p = Comp->Props;
+    for(int i = last_prop; i< p.size();i++) {
 
       // do not insert if already on first tab
       // this is the reason it was originally from back to front...
       // the 'pp' is the lasted property stepped over while filling the Swep tab
   //    if(p == pp)
   //      break;
-      if(p->display)
+      if(p.at(i)->display)
         s = tr("yes");
       else
         s = tr("no");
 
       // add Props into TableWidget
-      qDebug() << " Loading Comp->Props :" << p->Name << p->Value << p->display << p->Description ;
+      qDebug() << " Loading Comp->Props :" << p.at(i)->Name << p.at(i)->Value << p.at(i)->display << p.at(i)->Description ;
 
       if (row > prop->rowCount()-1) { // Add new rows
           prop->setRowCount(prop->rowCount()+1);
       }
 
       QTableWidgetItem *cell;
-      cell = new QTableWidgetItem(p->Name);
+      cell = new QTableWidgetItem(p.at(i)->Name);
       cell->setFlags(cell->flags() ^ Qt::ItemIsEditable);
       prop->setItem(row, 0, cell);
-      cell = new QTableWidgetItem(p->Value);
+      cell = new QTableWidgetItem(p.at(i)->Value);
       cell->setFlags(cell->flags() ^ Qt::ItemIsEditable);
       prop->setItem(row, 1, cell);
       cell = new QTableWidgetItem(s);
       cell->setFlags(cell->flags() ^ Qt::ItemIsEditable);
       prop->setItem(row, 2, cell);
-      cell = new QTableWidgetItem(p->Description);
+      cell = new QTableWidgetItem(p.at(i)->Description);
       cell->setFlags(cell->flags() ^ Qt::ItemIsEditable);
       prop->setItem(row, 3, cell);
 
@@ -897,25 +902,25 @@ void ComponentDialog::slotApplyInput()
    *  Only check if the widgets were created (pointers checks are 'true')
    */
   bool display;
-  Property *pp = Comp->Props.first();
+  auto pp = Comp->Props.begin();
   // apply all the new property values
 
   if(comboSim) {
     display = checkSim->isChecked();
-    if(pp->display != display) {
-      pp->display = display;
+    if((*pp)->display != display) {
+      (*pp)->display = display;
       changed = true;
     }
-    if(pp->Value != comboSim->currentText()) {
-      pp->Value = comboSim->currentText();
+    if((*pp)->Value != comboSim->currentText()) {
+      (*pp)->Value = comboSim->currentText();
       changed = true;
     }
-    pp = Comp->Props.next();
+    pp++;
   }
   if(comboType) {
     display = checkType->isChecked();
-    if(pp->display != display) {
-      pp->display = display;
+    if((*pp)->display != display) {
+      (*pp)->display = display;
       changed = true;
     }
     switch(comboType->currentIndex()) {
@@ -924,90 +929,90 @@ void ComponentDialog::slotApplyInput()
       case 3:  tmp = "const"; break;
       default: tmp = "lin";   break;
     }
-    if(pp->Value != tmp) {
-      pp->Value = tmp;
+    if((*pp)->Value != tmp) {
+      (*pp)->Value = tmp;
       changed = true;
     }
-    pp = Comp->Props.next();
+    pp++;
   }
   if(checkParam) if(checkParam->isEnabled()) {
     display = checkParam->isChecked();
-    if(pp->display != display) {
-      pp->display = display;
+    if((*pp)->display != display) {
+      (*pp)->display = display;
       changed = true;
     }
-    if(pp->Value != editParam->text()) {
-      pp->Value = editParam->text();
+    if((*pp)->Value != editParam->text()) {
+      (*pp)->Value = editParam->text();
       changed = true;
     }
-    pp = Comp->Props.next();
+    pp++;
   }
   if(editStart) {
     if(comboType->currentIndex() < 2) {
       display = checkStart->isChecked();
-      if(pp->display != display) {
-        pp->display = display;
+      if((*pp)->display != display) {
+        (*pp)->display = display;
         changed = true;
       }
-      pp->Name  = "Start";
-      if(pp->Value != editStart->text()) {
-        pp->Value = editStart->text();
+      (*pp)->Name  = "Start";
+      if((*pp)->Value != editStart->text()) {
+        (*pp)->Value = editStart->text();
         changed = true;
       }
-      pp = Comp->Props.next();
+      pp++;
 
       display = checkStop->isChecked();
-      if(pp->display != display) {
-        pp->display = display;
+      if((*pp)->display != display) {
+        (*pp)->display = display;
         changed = true;
       }
-      pp->Name  = "Stop";
-      if(pp->Value != editStop->text()) {
-        pp->Value = editStop->text();
+      (*pp)->Name  = "Stop";
+      if((*pp)->Value != editStop->text()) {
+        (*pp)->Value = editStop->text();
         changed = true;
       }
-      pp = Comp->Props.next();
+      pp++;
 
       display = checkNumber->isChecked();
-      if(pp->display != display) {
-        pp->display = display;
+      if((*pp)->display != display) {
+        (*pp)->display = display;
         changed = true;
       }
-      if((pp->Value != editNumber->text()) || (pp->Name != "Points")) {
-        pp->Value = editNumber->text();
-        pp->Name  = "Points";
+      if(((*pp)->Value != editNumber->text()) || ((*pp)->Name != "Points")) {
+        (*pp)->Value = editNumber->text();
+        (*pp)->Name  = "Points";
         changed = true;
       }
       qDebug() << "====> before ad"
-               << pp->Description;
+               << (*pp)->Description;
 
-      pp = Comp->Props.next();
+      pp++;
     }
     else {
       // If a value list is used, the properties "Start" and "Stop" are not
       // used. -> Call them "Symbol" to omit them in the netlist.
-      pp->Name = "Symbol";
-      pp->display = false;
-      pp = Comp->Props.next();
-      pp->Name = "Symbol";
-      pp->display = false;
-      pp = Comp->Props.next();
+      (*pp)->Name = "Symbol";
+      (*pp)->display = false;
+      pp++;
+      (*pp)->Name = "Symbol";
+      (*pp)->display = false;
+      pp++;
 
       display = checkValues->isChecked();
-      if(pp->display != display) {
-        pp->display = display;
+      if((*pp)->display != display) {
+        (*pp)->display = display;
         changed = true;
       }
       tmp = "["+editValues->text()+"]";
-      if((pp->Value != tmp) || (pp->Name != "Values")) {
-        pp->Value = tmp;
-        pp->Name  = "Values";
+      if(((*pp)->Value != tmp) || ((*pp)->Name != "Values")) {
+        (*pp)->Value = tmp;
+        (*pp)->Name  = "Values";
         changed = true;
       }
       qDebug() << "====> before ad"
-               << pp;
+               << pp.operator->();
 
-      pp = Comp->Props.next();
+      pp++;
     }
   }
 
@@ -1036,8 +1041,8 @@ void ComponentDialog::slotApplyInput()
        if (name != NameEdit->text())
          prop->item(row, 0)->setText(NameEdit->text());
 
-     // apply all the new property values in the ListView
-     for( int row = 0; row < prop->rowCount(); row++ ) {
+    // apply all the new property values in the ListView
+    for( int row = 0; row < prop->rowCount(); row++ ) {
 
        QString name  = prop->item(row, 0)->text();
        QString value = prop->item(row, 1)->text();
@@ -1047,26 +1052,26 @@ void ComponentDialog::slotApplyInput()
        qDebug() << "====>" <<name << value
                 << Comp->Props.count()
                 << prop->rowCount() +1
-                << pp;
+                << pp.operator->();
 
        display = (disp == tr("yes"));
-       if( pp ) {
+       if( pp != Comp->Props.end() ) {
 
-         if(pp->display != display) {
-             pp->display = display;
+         if((*pp)->display != display) {
+             (*pp)->display = display;
              changed = true;
          }
-         if(pp->Value != value) {
-            pp->Value = value;
+         if((*pp)->Value != value) {
+            (*pp)->Value = value;
             changed = true;
          }
-         if(pp->Name != name) {
-           pp->Name = name;   // override if previous one was removed
+         if((*pp)->Name != name) {
+           (*pp)->Name = name;   // override if previous one was removed
            changed = true;
          }
-         pp->Description = desc;
-         }
-       else {
+         (*pp)->Description = desc;
+         pp++;
+       }else {
          // if properties where added in the dialog
          // -> create new on the Comp
          Q_ASSERT(prop->rowCount() >= 0);
@@ -1075,21 +1080,16 @@ void ComponentDialog::slotApplyInput()
              Comp->Props.append(new Property(name, value, display, desc));
              changed = true;
          }
+       }
     }
-    pp = Comp->Props.next();
-  }
 
-  // original Comp still has properties? (removed some in the dialog?)
-  // if more properties than in ListView -> delete the rest
-  if(pp) {
-    pp = Comp->Props.prev();
-    Comp->Props.last();
-    while(pp != Comp->Props.current())
-      Comp->Props.remove();
-    changed = true;
-  }
-
- } // end if (item !=0)
+    // original Comp still has properties? (removed some in the dialog?)
+    // if more properties than in ListView -> delete the rest
+    if (pp != Comp->Props.end()) {
+      Comp->Props.erase(pp, Comp->Props.end());
+      changed = true;
+    }
+  } // end if (item !=0)
 
   if(changed) {
     int dx, dy;
diff --git a/qucs/components/dff_SR.cpp b/qucs/components/dff_SR.cpp
index 53efacc9..2f1463d7 100644
--- a/qucs/components/dff_SR.cpp
+++ b/qucs/components/dff_SR.cpp
@@ -44,7 +44,8 @@ dff_SR::dff_SR()
 Component * dff_SR::newOne()
 {
   dff_SR * p = new dff_SR();
-  p->Props.front()->Value = Props.front()->Value; 
+
+  p->Props.front()->Value = Props.front()->Value;
   p->recreate(0); 
   return p;
 }
diff --git a/qucs/components/digi_source.cpp b/qucs/components/digi_source.cpp
index 7b0efb32..8ff0518a 100644
--- a/qucs/components/digi_source.cpp
+++ b/qucs/components/digi_source.cpp
@@ -90,13 +90,14 @@ QString Digi_Source::netlist()
   s += " "+Ports.first()->Connection->Name;
   
   // output all properties
-  Props.first();   // first property not needed
-  Property *pp = Props.next();
-  s += " "+pp->Name+"=\""+pp->Value+"\"";
-  pp = Props.next();
-  s += " "+pp->Name+"=\"["+pp->Value+"]\"";
-  pp = Props.next();
-  s += " "+pp->Name+"=\""+pp->Value+"\"\n";
+     // first property not needed
+  auto pp = Props.begin();
+  pp++;
+  s += " "+(*pp)->Name+"=\""+(*pp)->Value+"\"";
+  pp++;
+  s += " "+(*pp)->Name+"=\"["+(*pp)->Value+"]\"";
+  pp++;
+  s += " "+(*pp)->Name+"=\""+(*pp)->Value+"\"\n";
 
   return s;
 }
@@ -165,7 +166,8 @@ QString Digi_Source::verilogCode(int NumPorts)
       State = '1';
     s += "  always begin\n";
 
-    t = Props.next()->Value.section(';',z,z).trimmed();
+    QString pv = Props.at(2)->Value;
+    t = pv.section(';',z,z).trimmed();
     while(!t.isEmpty()) {
       if(!misc::Verilog_Delay(t, Name))
         return t;    // time has not VHDL format
@@ -173,7 +175,7 @@ QString Digi_Source::verilogCode(int NumPorts)
       s += "   " + t + ";\n";
       State ^= 1;
       z++;
-      t = Props.current()->Value.section(';',z,z).trimmed();
+      t = pv.section(';',z,z).trimmed();
     }
   }
   else {  // truth table simulation
diff --git a/qucs/components/ecvs.cpp b/qucs/components/ecvs.cpp
index a8b69222..4ed58745 100644
--- a/qucs/components/ecvs.cpp
+++ b/qucs/components/ecvs.cpp
@@ -100,7 +100,7 @@ QString ecvs::netlist()
     s += " "+p1->Connection->Name;   // node names
 
   // output all properties
-  for(Property *p2 = Props.first(); p2 != 0; p2 = Props.next())
+  for(Property *p2 : Props)
     s += " "+p2->Name+"=\""+p2->Value+"\"";
 
   return s + "\n";
diff --git a/qucs/components/eqndefined.cpp b/qucs/components/eqndefined.cpp
index 63159320..ed759931 100644
--- a/qucs/components/eqndefined.cpp
+++ b/qucs/components/eqndefined.cpp
@@ -87,12 +87,10 @@ QString EqnDefined::netlist()
     s += " "+p1->Connection->Name;   // node names
 
   // output all properties
-  Property *p2 = Props.at(2);
-  while(p2) {
-    s += " "+p2->Name+"=\""+Name+"."+p2->Name+"\"";
-    e += "  Eqn:Eqn"+Name+p2->Name+" "+
-      Name+"."+p2->Name+"=\""+p2->Value+"\" Export=\"no\"\n";
-    p2 = Props.next();
+  for(int i = 2;i<Props.size();i++) {
+    s += " "+Props.at(i)->Name+"=\""+Name+"."+Props.at(i)->Name+"\"";
+    e += "  Eqn:Eqn"+Name+Props.at(i)->Name+" "+
+      Name+"."+Props.at(i)->Name+"=\""+Props.at(i)->Value+"\" Export=\"no\"\n";
   }
 
   return s+e;
@@ -291,12 +289,13 @@ void EqnDefined::createSymbol()
   }
 
   // adjust property names
-  Property * p1 = Props.at(2);
+  auto  p1 = Props.begin();
+  std::advance(p1, 2);
   for(i = 1; i <= Num; i++) {
-    p1->Name = "I"+QString::number(i);
-    p1 = Props.next();
-    p1->Name = "Q"+QString::number(i);
-    p1 = Props.next();
+    (*p1)->Name = "I"+QString::number(i);
+    p1++;
+    (*p1)->Name = "Q"+QString::number(i);
+    p1++;
   }
 
   // draw symbol
diff --git a/qucs/components/equation.cpp b/qucs/components/equation.cpp
index 8adce4e3..108428c3 100644
--- a/qucs/components/equation.cpp
+++ b/qucs/components/equation.cpp
@@ -63,7 +63,7 @@ QString Equation::verilogCode(int)
 {
   QString s;
   // output all equations
-  for(Property *pr = Props.first(); pr != 0; pr = Props.next())
+  for(Property *pr : Props)
     if(pr->Name != "Export")
       s += "  real "+pr->Name+"; initial "+pr->Name+" = "+pr->Value+";\n";
   return s;
@@ -74,7 +74,7 @@ QString Equation::vhdlCode(int)
 {
   QString s;
   // output all equations
-  for(Property *pr = Props.first(); pr != 0; pr = Props.next())
+  for(Property *pr : Props)
     if(pr->Name != "Export")
       s += "  constant "+pr->Name+" : time := "+pr->Value+";\n";
   return s;
diff --git a/qucs/components/ifile.cpp b/qucs/components/ifile.cpp
index 69731d64..1cf4dac7 100644
--- a/qucs/components/ifile.cpp
+++ b/qucs/components/ifile.cpp
@@ -100,12 +100,11 @@ QString iFile::netlist()
     s += " "+p1->Connection->Name;   // node names
 
   // output file properties
-  Property *p2 = Props.first();
-  s += " "+p2->Name+"=\"{"+getSubcircuitFile()+"}\"";
+  s += " "+Props.at(0)->Name+"=\"{"+getSubcircuitFile()+"}\"";
 
   // output all remaining properties
-  for(p2 = Props.next(); p2 != 0; p2 = Props.next())
-    s += " "+p2->Name+"=\""+p2->Value+"\"";
+  for(int i = 1; i < Props.size();i++)
+    s += " "+Props.at(i)->Name+"=\""+Props.at(i)->Value+"\"";
 
   return s + "\n";
 }
diff --git a/qucs/components/libcomp.cpp b/qucs/components/libcomp.cpp
index 96ec0425..eab40cd5 100644
--- a/qucs/components/libcomp.cpp
+++ b/qucs/components/libcomp.cpp
@@ -49,8 +49,8 @@ LibComp::LibComp()
 Component* LibComp::newOne()
 {
   LibComp *p = new LibComp();
-  p->Props.first()->Value = Props.first()->Value;
-  p->Props.next()->Value = Props.next()->Value;
+  p->Props.at(0)->Value = Props.at(0)->Value;
+  p->Props.at(1)->Value = Props.at(1)->Value;
   p->recreate(0);
   return p;
 }
@@ -87,7 +87,7 @@ int LibComp::loadSection(const QString& Name, QString& Section,
              QStringList *Includes, QStringList *Attach)
 {
   QDir Directory(QucsSettings.LibDir);
-  QFile file(misc::properAbsFileName(Directory.absoluteFilePath(Props.first()->Value + ".lib"), containingSchematic));
+  QFile file(misc::properAbsFileName(Directory.absoluteFilePath(Props.at(0)->Value + ".lib"), containingSchematic));
   if(!file.open(QIODevice::ReadOnly))
     return -1;
 
@@ -123,7 +123,7 @@ int LibComp::loadSection(const QString& Name, QString& Section,
   }
 
   // search component
-  Line = "\n<Component " + Props.next()->Value + ">";
+  Line = "\n<Component " + Props.at(1)->Value + ">";
   Start = Section.indexOf(Line);
   if(Start < 0)  return -4;  // component not found
   Start = Section.indexOf('\n', Start);
@@ -207,13 +207,9 @@ int LibComp::loadSymbol()
     z = loadSection("Model", Line);
     if(z < 0)  return z;
 
-    Component *pc = getComponentFromName(Line);
-    if(pc == 0)  return -20;
-
-    copyComponent(pc);
-
-    pc->Props.setAutoDelete(false);
-    delete pc;
+    std::shared_ptr<Component> pc(getComponentFromName(Line));
+    if(!pc)  return -20;
+    copyComponent(pc.get());
 
     return 1;
   }
@@ -306,8 +302,8 @@ bool LibComp::createSubNetlist(QTextStream *stream, QStringList &FileList,
 // -------------------------------------------------------
 QString LibComp::createType()
 {
-  QString Type = misc::properFileName(Props.first()->Value);
-  return misc::properName(Type + "_" + Props.next()->Value);
+  QString Type = misc::properFileName(Props.at(0)->Value);
+  return misc::properName(Type + "_" + Props.at(1)->Value);
 }
 
 // -------------------------------------------------------
@@ -323,8 +319,8 @@ QString LibComp::netlist()
   s += " Type=\""+createType()+"\"";   // type for subcircuit
 
   // output user defined parameters
-  for(Property *pp = Props.at(2); pp != 0; pp = Props.next())
-    s += " "+pp->Name+"=\""+pp->Value+"\"";
+  for(int i = 2;i<Props.size();i++)
+    s += " "+Props.at(i)->Name+"=\""+Props.at(i)->Value+"\"";
 
   return s + '\n';
 }
@@ -373,9 +369,9 @@ QString LibComp::spice_netlist(bool)
     s += " " + createType();
 
     // output user defined parameters
-    for(Property *pp = Props.at(2); pp != 0; pp = Props.next()) {
-      QString val = spicecompat::normalize_value(pp->Value);
-      s += " "+pp->Name+"="+val;
+    for(int i = 2;i<Props.size();i++) {
+      QString val = spicecompat::normalize_value(Props.at(i)->Value);
+      s += " "+Props.at(i)->Name+"="+val;
     }
     s +="\n";
 
diff --git a/qucs/components/mosfet.cpp b/qucs/components/mosfet.cpp
index 8405b88d..ba1f9917 100644
--- a/qucs/components/mosfet.cpp
+++ b/qucs/components/mosfet.cpp
@@ -38,8 +38,8 @@ MOSFET::MOSFET()
 Component* MOSFET::newOne()
 {
   MOSFET* p = new MOSFET();
-  p->Props.first()->Value = Props.first()->Value;
-  p->Props.next()->Value = Props.next()->Value;
+  p->Props.at(0)->Value = Props.at(0)->Value;
+  p->Props.at(1)->Value = Props.at(1)->Value;
   p->recreate(0);
   return p;
 }
@@ -62,8 +62,8 @@ Element* MOSFET::info_p(QString& Name, char* &BitmapFile, bool getNewOne)
 
   if(getNewOne) {
     MOSFET* p = new MOSFET();
-    p->Props.first()->Value = "pfet";
-    p->Props.next()->Value = "-1.0 V";
+    p->Props.at(0)->Value = "pfet";
+    p->Props.at(1)->Value = "-1.0 V";
     p->recreate(0);
     return p;
   }
@@ -78,8 +78,7 @@ Element* MOSFET::info_depl(QString& Name, char* &BitmapFile, bool getNewOne)
 
   if(getNewOne) {
     MOSFET* p = new MOSFET();
-    p->Props.first();
-    p->Props.next()->Value = "-1.0 V";
+    p->Props.at(1)->Value = "-1.0 V";
     p->recreate(0);
     return p;
   }
@@ -110,8 +109,8 @@ void MOSFET::createSymbol()
     Lines.append(new qucs::Line( -1,  0, -6,  5,QPen(Qt::darkBlue,2)));
   }
 
-  if((Props.next()->Value.trimmed().at(0) == '-') ==
-     (Props.first()->Value == "nfet"))
+  if((Props.at(1)->Value.trimmed().at(0) == '-') ==
+     (Props.at(0)->Value == "nfet"))
     Lines.append(new qucs::Line(-10, -8,-10,  8,QPen(Qt::darkBlue,2)));
   else
     Lines.append(new qucs::Line(-10, -4,-10,  4,QPen(Qt::darkBlue,2)));
@@ -135,7 +134,7 @@ QString MOSFET::netlist()
   s += " "+Ports.at(2)->Connection->Name;  // connect substrate to source
 
   // output all properties
-  for(Property *p2 = Props.first(); p2 != 0; p2 = Props.next())
+  for(Property *p2 : Props)
     s += " "+p2->Name+"=\""+p2->Value+"\"";
 
   return s + '\n';
diff --git a/qucs/components/mosfet_sub.cpp b/qucs/components/mosfet_sub.cpp
index 2c794814..ab63091d 100644
--- a/qucs/components/mosfet_sub.cpp
+++ b/qucs/components/mosfet_sub.cpp
@@ -142,8 +142,8 @@ MOSFET_sub::MOSFET_sub()
 Component* MOSFET_sub::newOne()
 {
   MOSFET_sub* p = new MOSFET_sub();
-  p->Props.first()->Value = Props.first()->Value;
-  p->Props.next()->Value = Props.next()->Value;
+  p->Props.at(0)->Value = Props.at(0)->Value;
+  p->Props.at(1)->Value = Props.at(1)->Value;
   p->recreate(0);
   return p;
 }
@@ -225,8 +225,8 @@ Element* MOSFET_sub::info_p(QString& Name,
 
   if(getNewOne) {
     MOSFET_sub* p = new MOSFET_sub();
-    p->Props.first()->Value = "pfet";
-    p->Props.next()->Value = "-1.0 V";
+    p->Props.at(0)->Value = "pfet";
+    p->Props.at(1)->Value = "-1.0 V";
     p->recreate(0);
     return p;
   }
@@ -242,8 +242,7 @@ Element* MOSFET_sub::info_depl(QString& Name,
 
   if(getNewOne) {
     MOSFET_sub* p = new MOSFET_sub();
-    p->Props.first();
-    p->Props.next()->Value = "-1.0 V";
+    p->Props.at(1)->Value = "-1.0 V";
     p->recreate(0);
     return p;
   }
@@ -267,7 +266,7 @@ void MOSFET_sub::createSymbol()
 
   Lines.append(new qucs::Line( -4, 24,  4, 20,QPen(Qt::darkBlue,2)));
 
-  if(Props.first()->Value == "nfet") {
+  if(Props.at(0)->Value == "nfet") {
     Lines.append(new qucs::Line( -9,  0, -4, -5,QPen(Qt::darkBlue,2)));
     Lines.append(new qucs::Line( -9,  0, -4,  5,QPen(Qt::darkBlue,2)));
   }
@@ -276,7 +275,7 @@ void MOSFET_sub::createSymbol()
     Lines.append(new qucs::Line( -1,  0, -6,  5,QPen(Qt::darkBlue,2)));
   }
 
-  if((Props.next()->Value.trimmed().at(0) == '-') ==
+  if((Props.at(1)->Value.trimmed().at(0) == '-') ==
      (Props.first()->Value == "nfet"))
     Lines.append(new qucs::Line(-10, -8,-10,  8,QPen(Qt::darkBlue,2)));
   else
diff --git a/qucs/components/msvia.cpp b/qucs/components/msvia.cpp
index b40d50af..bf6c44f2 100644
--- a/qucs/components/msvia.cpp
+++ b/qucs/components/msvia.cpp
@@ -80,7 +80,7 @@ QString MSvia::netlist()
   s += " " + Ports.first()->Connection->Name + " gnd";
 
   // output all properties
-  for(Property *p2 = Props.first(); p2 != 0; p2 = Props.next())
+  for(Property *p2 : Props)
     s += " "+p2->Name+"=\""+p2->Value+"\"";
 
   return s + '\n';
diff --git a/qucs/components/mutualx.cpp b/qucs/components/mutualx.cpp
index 43fe84d6..faca2f22 100644
--- a/qucs/components/mutualx.cpp
+++ b/qucs/components/mutualx.cpp
@@ -186,11 +186,12 @@ void MutualX::createSymbol()
   // in any case rewrite properties Name and Description
   // (when loading a component, added properties have a default name)
   // adjust coils names
-  Property * p1 = Props.at(1);
+  auto p1 = Props.begin();
+  ++p1;
   for(int i = 1; i <= Num; i++) {
-    p1->Name = "L"+QString::number(i);
-    p1->Description = QObject::tr("inductance of coil") + " " + QString::number(i);
-    p1 = Props.next();
+    (*p1)->Name = "L"+QString::number(i);
+    (*p1)->Description = QObject::tr("inductance of coil") + " " + QString::number(i);
+    p1++;
   }
   // adjust coupling coeffs names
   for(int i = 1,state=1; i < Num; i++) 
diff --git a/qucs/components/opt_sim.cpp b/qucs/components/opt_sim.cpp
index 73b7f098..96ea6178 100644
--- a/qucs/components/opt_sim.cpp
+++ b/qucs/components/opt_sim.cpp
@@ -72,7 +72,7 @@ QString Optimize_Sim::netlist()
 // -----------------------------------------------------------
 bool Optimize_Sim::createASCOFiles()
 {
-  Property* pp;
+
   QFile afile(QucsSettings.tempFilesDir.filePath("asco_netlist.cfg"));
   if(afile.open(QIODevice::WriteOnly)) {
     QTextStream stream(&afile);
@@ -88,62 +88,62 @@ bool Optimize_Sim::createASCOFiles()
     stream << "#\n\n";
 
     stream << "#DE#\n";
-    pp = Props.at(1);
+
     QString val;
-    val = pp->Value.section('|',0,0);
+    val = Props.at(1)->Value.section('|',0,0);
     stream << "choice of method:" << val << "\n";
-    val = pp->Value.section('|',1,1);
+    val = Props.at(1)->Value.section('|',1,1);
     stream << "maximum no. of iterations:" << val << "\n";
-    val = pp->Value.section('|',2,2);
+    val = Props.at(1)->Value.section('|',2,2);
     stream << "Output refresh cycle:" << val << "\n";
-    val = pp->Value.section('|',3,3);
+    val = Props.at(1)->Value.section('|',3,3);
     stream << "No. of parents NP:" << val << "\n";
-    val= pp->Value.section('|',4,4);
+    val= Props.at(1)->Value.section('|',4,4);
     stream << "Constant F:" << val << "\n";
-    val = pp->Value.section('|',5,5);
+    val = Props.at(1)->Value.section('|',5,5);
     stream << "Crossing Over factor CR:" << val << "\n";
-    val = pp->Value.section('|',6,6);
+    val = Props.at(1)->Value.section('|',6,6);
     stream << "Seed for pseudo random number generator:" << val << "\n";
-    val = pp->Value.section('|',7,7);
+    val = Props.at(1)->Value.section('|',7,7);
     stream << "Minimum Cost Variance:" << val << "\n";
-    val = pp->Value.section('|',8,8);
+    val = Props.at(1)->Value.section('|',8,8);
     stream << "Cost objectives:" << val << "\n";
-    val = pp->Value.section('|',9,9);
+    val = Props.at(1)->Value.section('|',9,9);
     stream << "Cost constraints:" << val << "\n";
     stream << "#\n\n";
 
     stream << "# Parameters #\n";
-    int i=1;
-    for(pp = Props.at(2); pp != 0; pp = Props.next(), i++) {
-      if(pp->Name == "Var") {
-	stream << "Parameter " << i << ":";
-	val = pp->Value.section('|',0,0);
+
+    for(int i= 2; i < Props.size();i++) {
+      if(Props.at(i)->Name == "Var") {
+        stream << "Parameter " << i-1 << ":";
+        val = Props.at(i)->Value.section('|',0,0);
 	stream << "#" << val << "#" << ":";
-	val = pp->Value.section('|',2,2);
+        val = Props.at(i)->Value.section('|',2,2);
 	stream << val << ":";
-	val = pp->Value.section('|',3,3);
+        val = Props.at(i)->Value.section('|',3,3);
 	stream << val << ":";
-	val = pp->Value.section('|',4,4);
+        val = Props.at(i)->Value.section('|',4,4);
 	stream << val << ":";
-	val = pp->Value.section('|',5,5);
+        val = Props.at(i)->Value.section('|',5,5);
 	stream << val << ":";
-	val = pp->Value.section('|',1,1);
+        val = Props.at(i)->Value.section('|',1,1);
 	stream << ((val == "yes") ? "OPT" : "---") << "\n";
       }
     }
     stream << "#\n\n";
 
     stream << "# Measurements #\n";
-    for(pp = Props.at(2); pp != 0; pp = Props.next(), i++) {
-      if(pp->Name == "Goal") {
-	val = pp->Value.section('|',1,1);
+    for(int i= 2; i < Props.size();i++) {
+      if(Props.at(i)->Name == "Goal") {
+        val = Props.at(i)->Value.section('|',1,1);
 	QString Type, Value;
-	Value = pp->Value.section('|',2,2);
+        Value = Props.at(i)->Value.section('|',2,2);
 	if (val == "MIN" || val == "MAX" || val == "MON") {
 	  Value = "---";
 	}
 	Type = val;
-	val = pp->Value.section('|',0,0);
+        val = Props.at(i)->Value.section('|',0,0);
 	stream << val <<  ":"
 	       << "---" << ":"
 	       << Type << ":" << Value << "\n";
@@ -165,9 +165,9 @@ bool Optimize_Sim::createASCOFiles()
       return false;
   }      
 
-  for(pp = Props.at(2); pp != 0; pp = Props.next()) {
-    if(pp->Name == "Goal") {
-      QString VarName = pp->Value.section('|',0,0);
+  for(int i= 2; i < Props.size();i++) {
+    if(Props.at(i)->Name == "Goal") {
+      QString VarName = Props.at(i)->Value.section('|',0,0);
       QFile efile(ExtractDir.filePath(VarName));
       if(efile.open(QIODevice::WriteOnly)) {
     QTextStream stream(&efile);
@@ -195,11 +195,10 @@ bool Optimize_Sim::createASCOFiles()
  */
 bool Optimize_Sim::createASCOnetlist()
 {
-  Property* pp;
   QStringList vars;
-  for(pp = Props.at(2); pp != 0; pp = Props.next()) {
-    if(pp->Name == "Var") {
-      vars += pp->Value.section('|',0,0);
+  for(int i= 2; i < Props.size();i++) {
+    if(Props.at(i)->Name == "Var") {
+      vars += Props.at(i)->Value.section('|',0,0);
     }
   }
 
@@ -245,11 +244,10 @@ bool Optimize_Sim::createASCOnetlist()
 bool Optimize_Sim::loadASCOout()
 {
   bool changed = false;
-  Property* pp;
   QStringList vars;
-  for(pp = Props.at(2); pp != 0; pp = Props.next()) {
-    if(pp->Name == "Var") {
-      vars += pp->Value.section('|',0,0);
+  for(int i= 2; i < Props.size();i++) {
+    if(Props.at(i)->Name == "Var") {
+      vars += Props.at(i)->Value.section('|',0,0);
     }
   }
 
@@ -267,21 +265,21 @@ bool Optimize_Sim::loadASCOout()
     QString Name = *it;
     Name = Name.trimmed();
     if(vars.contains(Name)) {
-      for(pp = Props.at(2); pp != 0; pp = Props.next()) {
-	if(pp->Name == "Var") {
+      for(int i= 2; i < Props.size();i++) {
+        if(Props.at(i)->Name == "Var") {
 	  QString val[6];
-	  val[0] = pp->Value.section('|',0,0); // variable name
+          val[0] = Props.at(i)->Value.section('|',0,0); // variable name
 	  if(val[0]==Name) {
-	    val[1] = pp->Value.section('|',1,1);
-	    val[2] = pp->Value.section('|',2,2);
-	    val[3] = pp->Value.section('|',3,3);
-	    val[4] = pp->Value.section('|',4,4);
-	    val[5] = pp->Value.section('|',5,5);
+            val[1] = Props.at(i)->Value.section('|',1,1);
+            val[2] = Props.at(i)->Value.section('|',2,2);
+            val[3] = Props.at(i)->Value.section('|',3,3);
+            val[4] = Props.at(i)->Value.section('|',4,4);
+            val[5] = Props.at(i)->Value.section('|',5,5);
 	    ++it; // field after variable name is its value
 	    QString Value = *it;
 	    Value = Value.trimmed();
 	    val[2] = Value;
-	    pp->Value = val[0] + "|" + val[1] + "|" + val[2] + "|" +
+            Props.at(i)->Value = val[0] + "|" + val[1] + "|" + val[2] + "|" +
 	      val[3] + "|" + val[4] + "|" + val[5];
 	    changed = true;
 	    break;
diff --git a/qucs/components/optimizedialog.cpp b/qucs/components/optimizedialog.cpp
index f6f8a6ae..770c5f1c 100644
--- a/qucs/components/optimizedialog.cpp
+++ b/qucs/components/optimizedialog.cpp
@@ -380,8 +380,9 @@ OptimizeDialog::OptimizeDialog(Optimize_Sim *c_, Schematic *d_)
   NameEdit->setText(Comp->Name);
 
   QTableWidgetItem *item;
-  for(pp = Comp->Props.at(2); pp != 0; pp = Comp->Props.next()) {
-    if(pp->Name == "Var") {
+
+  for(int i = 2;i< Comp->Props.size();i++) {
+    if(Comp->Props.at(i)->Name == "Var") {
       QStringList ValueSplit = pp->Value.split("|");
       int row = VarTable->rowCount();
       VarTable->insertRow(row);
@@ -757,7 +758,9 @@ void OptimizeDialog::slotApply()
     changed = true;
   }
 
-  Property *pp = Comp->Props.at(2);
+  auto pp = Comp->Props.begin();
+  ++pp;
+  ++pp;
   int row;
   // apply all the new property values in the TableWidget
   for (row = 0; row < VarTable->rowCount(); ++row) {
@@ -793,13 +796,13 @@ void OptimizeDialog::slotApply()
     }
     Prop = propList.join("|");
 
-    if(pp) {
-      if(pp->Name != "Var") {
-        pp->Name = "Var";
+    if(pp != Comp->Props.end()) {
+      if((*pp)->Name != "Var") {
+        (*pp)->Name = "Var";
         changed = true;
       }
-      if(pp->Value != Prop) {
-        pp->Value = Prop;
+      if((*pp)->Value != Prop) {
+        (*pp)->Value = Prop;
         changed = true;
       }
     }
@@ -807,7 +810,7 @@ void OptimizeDialog::slotApply()
       Comp->Props.append(new Property("Var", Prop, false, ""));
       changed = true;
     }
-    pp = Comp->Props.next();
+    pp++;
   }
 
   for (row = 0; row < GoalTable->rowCount(); ++row) {
@@ -830,13 +833,13 @@ void OptimizeDialog::slotApply()
     propList << GoalTable->item(row, 2)->text();
     Prop = propList.join("|");
 
-    if(pp) {
-      if(pp->Name != "Goal") {
-        pp->Name = "Goal";
+    if(pp != Comp->Props.end()) {
+      if((*pp)->Name != "Goal") {
+        (*pp)->Name = "Goal";
         changed = true;
       }
-      if(pp->Value != Prop) {
-        pp->Value = Prop;
+      if((*pp)->Value != Prop) {
+        (*pp)->Value = Prop;
         changed = true;
       }
     }
@@ -844,15 +847,12 @@ void OptimizeDialog::slotApply()
       Comp->Props.append(new Property("Goal", Prop, false, ""));
       changed = true;
     }
-    pp = Comp->Props.next();
+    pp++;
   }
 
   // if more properties than in ListView -> delete the rest
-  if(pp) {
-    pp = Comp->Props.prev();
-    Comp->Props.last();
-    while(pp != Comp->Props.current())
-      Comp->Props.remove();
+  if(pp != Comp->Props.end()) {
+    Comp->Props.erase(pp, Comp->Props.end());
     changed = true;
   }
 
@@ -876,10 +876,9 @@ void OptimizeDialog::slotCreateEqn()
               //<Model Name ShowName cx cy tx ty mirroredX rotate
               "<Eqn OptValues 1 0 0 -28 15 0 0 ";
 
- Property *pp;
- for(pp = Comp->Props.at(2); pp != 0; pp = Comp->Props.next()) {
-   if(pp->Name == "Var") { // property is an optimization variable
-      QStringList ValueSplit = pp->Value.split("|");
+  for(int i = 2;i<Comp->Props.size();i++) {
+    if(Comp->Props.at(i)->Name == "Var") { // property is an optimization variable
+      QStringList ValueSplit = Comp->Props.at(i)->Value.split("|");
       // "Name" = "initial (current) value"
       s += "\"" + ValueSplit.at(0) + "=" + ValueSplit.at(2) + "\" 1 ";
    }
@@ -922,9 +921,9 @@ void OptimizeDialog::slotSetPrecision(const QPoint& pos)
     int row = 0;
     Property *pp;
     QTableWidgetItem *item;
-    for(pp = Comp->Props.at(2); pp != 0; pp = Comp->Props.next()) {
-      if(pp->Name == "Var") {
-	QStringList ValueSplit = pp->Value.split("|");
+    for(int i = 2; i< Comp->Props.size(); i++) {
+      if(Comp->Props.at(i)->Name == "Var") {
+        QStringList ValueSplit = Comp->Props.at(i)->Value.split("|");
 	// 'initial' column
 	item = VarTable->item(row++, 2);
 	item->setText(QString::number(ValueSplit.at(2).toDouble(), 'g', numPrec));
diff --git a/qucs/components/param_sweep.cpp b/qucs/components/param_sweep.cpp
index 8ff292ca..76a85a2f 100644
--- a/qucs/components/param_sweep.cpp
+++ b/qucs/components/param_sweep.cpp
@@ -64,22 +64,18 @@ Element* Param_Sweep::info(QString& Name, char* &BitmapFile, bool getNewOne)
 
 void Param_Sweep::recreate(Schematic*)
 {
-  Property *pp = Props.at(1);
-  Props.next();
-  if((pp->Value == "list") || (pp->Value == "const")) {
+  if((Props.at(1)->Value == "list") || (Props.at(1)->Value == "const")) {
     // Call them "Symbol" to omit them in the netlist.
-    pp = Props.next();
-    pp->Name = "Symbol";
-    pp->display = false;
-    pp = Props.next();
-    pp->Name = "Symbol";
-    pp->display = false;
-    Props.next()->Name = "Values";
+    Props.at(2)->Name = "Symbol";
+    Props.at(2)->display = false;
+    Props.at(3)->Name = "Symbol";
+    Props.at(3)->display = false;
+    Props.at(4)->Name = "Values";
   }
   else {
-    Props.next()->Name = "Start";
-    Props.next()->Name = "Stop";
-    Props.next()->Name = "Points";
+    Props.at(2)->Name = "Start";
+    Props.at(3)->Name = "Stop";
+    Props.at(4)->Name = "Points";
   }
 }
 
diff --git a/qucs/components/potentiometer.cpp b/qucs/components/potentiometer.cpp
index 2965fa71..60f7aa4c 100644
--- a/qucs/components/potentiometer.cpp
+++ b/qucs/components/potentiometer.cpp
@@ -59,7 +59,7 @@ potentiometer::potentiometer()
 Component * potentiometer::newOne()
 {
   potentiometer * p = new potentiometer();
-  p->Props.front()->Value = Props.front()->Value; 
+  p->Props.front()->Value = Props.front()->Value;
   p->recreate(0); 
   return p;
 }
diff --git a/qucs/components/rfedd.cpp b/qucs/components/rfedd.cpp
index 5e686f4d..bfe3d9d6 100644
--- a/qucs/components/rfedd.cpp
+++ b/qucs/components/rfedd.cpp
@@ -89,19 +89,17 @@ QString RFedd::netlist()
     s += " "+p1->Connection->Name;   // node names
 
   // output all properties
-  Property *p2;
-  p2 = Props.at(0);
-  s += " "+p2->Name+"=\""+p2->Value+"\"";
-  p = p2->Value;
-  p2 = Props.at(2);
-  s += " "+p2->Name+"=\""+p2->Value+"\"";
-  p2 = Props.at(3);
-  while(p2) {
-    n = p2->Name.mid(1);
-    s += " "+p2->Name+"=\""+Name+"."+p+n+"\"";
-    e += "  Eqn:Eqn"+Name+p2->Name+" "+
-      Name+"."+p+n+"=\""+p2->Value+"\" Export=\"no\"\n";
-    p2 = Props.next();
+
+         // output all properties
+  s += " "+Props.at(0)->Name+"=\""+Props.at(0)->Value+"\"";
+  p = Props.at(0)->Value;
+  s += " "+Props.at(2)->Name+"=\""+Props.at(2)->Value+"\"";
+
+  for (int i = 3; i < int(Props.size()); ++i) {
+    n = Props.at(i)->Name.mid(1);
+    s += " "+Props.at(i)->Name+"=\""+Name+"."+p+n+"\"";
+    e += "  Eqn:Eqn"+Name+Props.at(i)->Name+" "+
+         Name+"."+p+n+"=\""+Props.at(i)->Value+"\" Export=\"no\"\n";
   }
 
   return s+e;
diff --git a/qucs/components/rfedd2p.cpp b/qucs/components/rfedd2p.cpp
index ecd72367..b7132a1e 100644
--- a/qucs/components/rfedd2p.cpp
+++ b/qucs/components/rfedd2p.cpp
@@ -87,19 +87,15 @@ QString RFedd2P::netlist()
     s += " "+p1->Connection->Name;   // node names
 
   // output all properties
-  Property *p2;
-  p2 = Props.at(0);
-  s += " "+p2->Name+"=\""+p2->Value+"\"";
-  p = p2->Value;
-  p2 = Props.at(1);
-  s += " "+p2->Name+"=\""+p2->Value+"\"";
-  p2 = Props.at(2);
-  while(p2) {
-    n = p2->Name.mid(1);
-    s += " "+p2->Name+"=\""+Name+"."+p+n+"\"";
-    e += "  Eqn:Eqn"+Name+p2->Name+" "+
-      Name+"."+p+n+"=\""+p2->Value+"\" Export=\"no\"\n";
-    p2 = Props.next();
+  // output all properties
+  s += " "+Props.at(0)->Name+"=\""+Props.at(0)->Value+"\"";
+  p = Props.at(0)->Value;
+  s += " "+Props.at(1)->Name+"=\""+Props.at(1)->Value+"\"";
+  for (int i = 2; i < int(Props.size()); ++i) {
+    n = Props.at(i)->Name.mid(1);
+    s += " "+Props.at(i)->Name+"=\""+Name+"."+p+n+"\"";
+    e += "  Eqn:Eqn"+Name+Props.at(i)->Name+" "+
+         Name+"."+p+n+"=\""+Props.at(i)->Value+"\" Export=\"no\"\n";
   }
 
   return s+e;
diff --git a/qucs/components/sp_sim.cpp b/qucs/components/sp_sim.cpp
index 98b14c9b..c14e4fa8 100644
--- a/qucs/components/sp_sim.cpp
+++ b/qucs/components/sp_sim.cpp
@@ -73,21 +73,18 @@ Element* SP_Sim::info(QString& Name, char* &BitmapFile, bool getNewOne)
 
 void SP_Sim::recreate(Schematic*)
 {
-  Property *pp = Props.first();
-  if((pp->Value == "list") || (pp->Value == "const")) {
+  if((Props.at(0)->Value == "list") || (Props.at(0)->Value == "const")) {
     // Call them "Symbol" to omit them in the netlist.
-    pp = Props.next();
-    pp->Name = "Symbol";
-    pp->display = false;
-    pp = Props.next();
-    pp->Name = "Symbol";
-    pp->display = false;
-    Props.next()->Name = "Values";
+    Props.at(1)->Name = "Symbol";
+    Props.at(1)->display = false;
+    Props.at(2)->Name = "Symbol";
+    Props.at(2)->display = false;
+    Props.at(3)->Name = "Values";
   }
   else {
-    Props.next()->Name = "Start";
-    Props.next()->Name = "Stop";
-    Props.next()->Name = "Points";
+    Props.at(1)->Name = "Start";
+    Props.at(2)->Name = "Stop";
+    Props.at(3)->Name = "Points";
   }
 }
 
diff --git a/qucs/components/sparamfile.cpp b/qucs/components/sparamfile.cpp
index 32ccf057..809fd6f6 100644
--- a/qucs/components/sparamfile.cpp
+++ b/qucs/components/sparamfile.cpp
@@ -120,20 +120,16 @@ QString SParamFile::netlist()
     s += " "+p1->Connection->Name;   // node names
 
   // output all properties
-  Property *p2 = Props.first();
-  s += " "+p2->Name+"=\"{"+getSubcircuitFile()+"}\"";
+  s += " "+Props.at(0)->Name+"=\"{"+getSubcircuitFile()+"}\"";
 
   // data type
-  p2 = Props.next();
-  s += " "+p2->Name+"=\""+p2->Value+"\"";
+  s += " "+Props.at(1)->Name+"=\""+Props.at(1)->Value+"\"";
 
   // interpolator type
-  p2 = Props.next();
-  s += " "+p2->Name+"=\""+p2->Value+"\"";
+  s += " "+Props.at(2)->Name+"=\""+Props.at(2)->Value+"\"";
 
   // DC property
-  p2 = Props.next();
-  s += " "+p2->Name+"=\""+p2->Value+"\"\n";
+  s += " "+Props.at(3)->Name+"=\""+Props.at(3)->Value+"\"\n";
 
   return s;
 }
diff --git a/qucs/components/spicedialog.cpp b/qucs/components/spicedialog.cpp
index f25240e3..f9a25390 100644
--- a/qucs/components/spicedialog.cpp
+++ b/qucs/components/spicedialog.cpp
@@ -157,7 +157,7 @@ SpiceDialog::SpiceDialog(QucsApp* App_, SpiceFile *c, Schematic *d)
   changed = false;
 
   // insert all properties into the ListBox
-  Property *pp = Comp->Props.first();
+  auto pp = Comp->Props.at(0);
   FileEdit->setText(pp->Value);
   FileCheck->setChecked(pp->display);
   SimCheck->setChecked(Comp->Props.at(2)->Value == "yes");
@@ -226,15 +226,15 @@ void SpiceDialog::slotButtApply()
   }
 
   // apply all the new property values
-  Property *pp = Comp->Props.first();
-  if(pp->Value != FileEdit->text())
+  auto pp = Comp->Props.begin();
+  if((*pp)->Value != FileEdit->text())
   {
-    pp->Value = FileEdit->text();
+    (*pp)->Value = FileEdit->text();
     changed = true;
   }
-  if(pp->display != FileCheck->isChecked())
+  if((*pp)->display != FileCheck->isChecked())
   {
-    pp->display = FileCheck->isChecked();
+    (*pp)->display = FileCheck->isChecked();
     changed = true;
   }
 
@@ -246,26 +246,26 @@ void SpiceDialog::slotButtApply()
     }
     tmp += "_net" + PortsList->item(i)->text();   // chosen ports
   }
-  pp = Comp->Props.next();
-  if(pp->Value != tmp)
+  pp++;
+  if((*pp)->Value != tmp)
   {
-    pp->Value = tmp;
+    (*pp)->Value = tmp;
     changed = true;
   }
-  pp = Comp->Props.next();
-  if((pp->Value=="yes") != SimCheck->isChecked())
+  pp++;
+  if(((*pp)->Value=="yes") != SimCheck->isChecked())
   {
-    pp->Value = ((SimCheck->isChecked())? "yes" : "no");
+    (*pp)->Value = ((SimCheck->isChecked())? "yes" : "no");
     changed = true;
   }
-  if(pp->Value != "yes") {
+  if((*pp)->Value != "yes") {
     Comp->withSim = false;
   }
 
-  pp = Comp->Props.next();
-  if(pp->Value != PrepCombo->currentText())
+  pp++;
+  if((*pp)->Value != PrepCombo->currentText())
   {
-    pp->Value = PrepCombo->currentText();
+    (*pp)->Value = PrepCombo->currentText();
     changed = true;
   }
 
diff --git a/qucs/components/subcircuit.cpp b/qucs/components/subcircuit.cpp
index 1359ad5f..a8207c1e 100644
--- a/qucs/components/subcircuit.cpp
+++ b/qucs/components/subcircuit.cpp
@@ -214,7 +214,7 @@ QString Subcircuit::netlist()
   s += " Type=\""+misc::properName(f)+"\"";
 
   // output all user defined properties
-  for(Property *pp = Props.next(); pp != 0; pp = Props.next())
+  for(Property *pp : Props)
     s += " "+pp->Name+"=\""+pp->Value+"\"";
   return s + '\n';
 }
@@ -230,7 +230,7 @@ QString Subcircuit::spice_netlist(bool)
         s += " "+nam;   // node names
     }
     s += " " + misc::properName(f);
-    for(Property *pp = Props.next(); pp != 0; pp = Props.next()) {
+    for(Property *pp : Props) {
         s += QString(" %1=%2").arg(pp->Name).arg(spicecompat::normalize_value(pp->Value));
     }
     s += "\n";
@@ -244,12 +244,12 @@ QString Subcircuit::vhdlCode(int)
   QString s = "  " + Name + ": entity Sub_" + misc::properName(f);
 
   // output all user defined properties
-  Property *pr = Props.next();
-  if (pr) {
+  if (Props.at(1) != nullptr) {
     s += " generic map (";
-    s += pr->Value;
-    for(pr = Props.next(); pr != 0; pr = Props.next())
-      s += ", " + pr->Value;
+    s += Props.at(1)->Value;
+    for(int i = 2; i < Props.size(); i++){
+      s += ", " + Props.at(i)->Value;
+    }
     s += ")";
   }
 
@@ -275,12 +275,11 @@ QString Subcircuit::verilogCode(int)
   QString s = "  Sub_" + misc::properName(f);
 
   // output all user defined properties
-  Property *pr = Props.next();
-  if (pr) {
+  if (Props.at(1) != nullptr) {
     s += " #(";
-    s += misc::Verilog_Param(pr->Value);
-    for(pr = Props.next(); pr != 0; pr = Props.next())
-      s += ", " + misc::Verilog_Param(pr->Value);
+    s += misc::Verilog_Param(Props.at(1)->Value);
+    for(int i = 2; i < Props.size(); i++)
+      s += ", " + misc::Verilog_Param(Props.at(i)->Value);
     s += ")";
   }
 
diff --git a/qucs/components/switch.cpp b/qucs/components/switch.cpp
index d0810adc..7d242f5d 100644
--- a/qucs/components/switch.cpp
+++ b/qucs/components/switch.cpp
@@ -76,12 +76,10 @@ QString Switch::netlist()
   s += " "+Ports.at(1)->Connection->Name;
 
   // output all properties
-  Property *p2 = Props.first();
-  s += " "+p2->Name+"=\""+p2->Value+"\"";
-  p2 = Props.next();
-  s += " "+p2->Name+"=\"["+p2->Value+"]\"";
-  for(p2 = Props.next(); p2 != 0; p2 = Props.next())
-    s += " "+p2->Name+"=\""+p2->Value+"\"";
+  s += " "+Props.at(0)->Name+"=\""+Props.at(0)->Value+"\"";
+  s += " "+Props.at(1)->Name+"=\"["+Props.at(1)->Value+"]\"";
+  for(int i=2;i<Props.size();i++)
+    s += " "+Props.at(i)->Name+"=\""+Props.at(i)->Value+"\"";
 
   return s + '\n';
 }
diff --git a/qucs/components/tr_sim.cpp b/qucs/components/tr_sim.cpp
index 1a624574..82f31d95 100644
--- a/qucs/components/tr_sim.cpp
+++ b/qucs/components/tr_sim.cpp
@@ -119,20 +119,17 @@ QString TR_Sim::spice_netlist(bool isXyce)
 
 void TR_Sim::recreate(Schematic*)
 {
-  Property *pp = Props.first();
-  if((pp->Value == "list") || (pp->Value == "const")) {
+  if((Props.at(0)->Value == "list") || (Props.at(0)->Value == "const")) {
     // Call them "Symbol" to omit them in the netlist.
-    pp = Props.next();
-    pp->Name = "Symbol";
-    pp->display = false;
-    pp = Props.next();
-    pp->Name = "Symbol";
-    pp->display = false;
-    Props.next()->Name = "Values";
+    Props.at(1)->Name = "Symbol";
+    Props.at(1)->display = false;
+    Props.at(2)->Name = "Symbol";
+    Props.at(2)->display = false;
+    Props.at(3)->Name = "Values";
   }
   else {
-    Props.next()->Name = "Start";
-    Props.next()->Name = "Stop";
-    Props.next()->Name = "Points";
+    Props.at(1)->Name = "Start";
+    Props.at(2)->Name = "Stop";
+    Props.at(3)->Name = "Points";
   }
 }
diff --git a/qucs/components/vfile.cpp b/qucs/components/vfile.cpp
index 6a2f6375..44ea934d 100644
--- a/qucs/components/vfile.cpp
+++ b/qucs/components/vfile.cpp
@@ -103,12 +103,11 @@ QString vFile::netlist()
     s += " "+p1->Connection->Name;   // node names
 
   // output file properties
-  Property *p2 = Props.first();
-  s += " "+p2->Name+"=\"{"+getSubcircuitFile()+"}\"";
+  s += " "+Props.at(0)->Name+"=\"{"+getSubcircuitFile()+"}\"";
 
   // output all remaining properties
-  for(p2 = Props.next(); p2 != 0; p2 = Props.next())
-    s += " "+p2->Name+"=\""+p2->Value+"\"";
+  for(int i = 1;i<Props.size();i++)
+    s += " "+Props.at(i)->Name+"=\""+Props.at(i)->Value+"\"";
 
   return s + "\n";
 }
diff --git a/qucs/components/vhdlfile.cpp b/qucs/components/vhdlfile.cpp
index f354adf2..bfbc5f1f 100644
--- a/qucs/components/vhdlfile.cpp
+++ b/qucs/components/vhdlfile.cpp
@@ -72,12 +72,11 @@ QString VHDL_File::vhdlCode(int)
     s = "  " + Name + ": entity " + EntityName;
 
     // output all generic properties
-    Property *pr = Props.at(1);
-    if (pr) {
+    if (Props.at(1) != nullptr) {
       s += " generic map (";
-      s += pr->Value;
-      for(pr = Props.next(); pr != 0; pr = Props.next())
-	s += ", " + pr->Value;
+      s += Props.at(1)->Value;
+      for(int i = 2; i < Props.size();i++)
+        s += ", " + Props.at(i)->Value;
       s += ")";
     }
 
@@ -177,21 +176,22 @@ void VHDL_File::createSymbol()
   No = 0;
   if(!GenNames.isEmpty())
     No = (GenNames.count(',')) + 1;
-  Property * pr = Props.at(1);
+  auto pr = Props.begin();
+  ++pr;
   for(i=0; i<No; i++) {
-    if (!pr) {
-      pr = new Property(GenNames.section(',', i, i),
+    if (pr == Props.end()) {
+      auto newProp = new Property(GenNames.section(',', i, i),
 			GenDefs.section(',', i, i), true,
 			QObject::tr("generic variable")+
 			" "+QString::number(i+1));
-      Props.append(pr);
-      pr = 0;
+      Props.append(newProp);
     }
     else {
-      pr->Description =
+
+      (*pr)->Description =
 	QObject::tr("generic variable")+" "+QString::number(i+1);
-      pr->Name = GenNames.section(',', i, i);
-      pr = Props.next();
+      (*pr)->Name = GenNames.section(',', i, i);
+      pr++;
     }
   }
   // remove remaining properties if necessary
diff --git a/qucs/dialogs/changedialog.cpp b/qucs/dialogs/changedialog.cpp
index d00c9244..d9c006ec 100644
--- a/qucs/dialogs/changedialog.cpp
+++ b/qucs/dialogs/changedialog.cpp
@@ -180,7 +180,7 @@ void ChangeDialog::slotButtReplace()
     if(matches(pc->Model)) {
       QRegularExpressionMatch match = Expr.match(pc->Name);
       if(match.hasMatch())
-        for(Property *pp = pc->Props.first(); pp!=0; pp = pc->Props.next())
+        for(const auto& pp : pc->Props)
           if(pp->Name == PropNameEdit->currentText()) {
             pb = new QCheckBox(pc->Name);
             Dia_Box->addWidget(pb);   
@@ -232,7 +232,7 @@ void ChangeDialog::slotButtReplace()
     for(pc = Doc->Components->first(); pc!=0; pc = Doc->Components->next()) {
       if(pb->text() != pc->Name)  continue;
 
-      for(Property *pp = pc->Props.first(); pp!=0; pp = pc->Props.next()) {
+      for(auto pp : pc->Props) {
         if(pp->Name != PropNameEdit->currentText())  continue;
 
         int tx_Dist, ty_Dist, tmp;
diff --git a/qucs/dialogs/fillfromspicedialog.cpp b/qucs/dialogs/fillfromspicedialog.cpp
index dacfdf48..93d2de81 100644
--- a/qucs/dialogs/fillfromspicedialog.cpp
+++ b/qucs/dialogs/fillfromspicedialog.cpp
@@ -171,7 +171,7 @@ QString fillFromSpiceDialog::convertNumNotation(const QString &value)
 
 void fillFromSpiceDialog::fillCompProps()
 {
-  for(Property *p = Comp->Props.first(); p != 0; p = Comp->Props.next()) {
+  for(Property *p : Comp->Props) {
     QString name = p->Name;
     name = name.toLower();
     if (parsedProps.contains(name)) {
diff --git a/qucs/extsimkernels/spicelibcompdialog.cpp b/qucs/extsimkernels/spicelibcompdialog.cpp
index d24c080d..18f46e94 100644
--- a/qucs/extsimkernels/spicelibcompdialog.cpp
+++ b/qucs/extsimkernels/spicelibcompdialog.cpp
@@ -474,25 +474,25 @@ bool SpiceLibCompDialog::setCompProps()
     sympath = QDir(sch_dir).relativeFilePath(sympath);
   }
 
-  Property *pp = comp->Props.first();
-  pp->Value = libpath;
-  pp->display = chbShowLib->isChecked();
-  pp = comp->Props.next();
-  pp->Value = cbxSelectSubcir->currentText();
-  pp->display = chbShowModel->isChecked();
-  pp = comp->Props.next();
+  auto pp = comp->Props.begin();
+  (*pp)->Value = libpath;
+  (*pp)->display = chbShowLib->isChecked();
+  pp++;
+  (*pp)->Value = cbxSelectSubcir->currentText();
+  (*pp)->display = chbShowModel->isChecked();
+  pp++;
   if (rbAutoSymbol->isChecked()) {
-    pp->Value = "auto";
+    (*pp)->Value = "auto";
   } else if (rbSymFromTemplate->isChecked()) {
-    pp->Value = listSymPattern->currentItem()->text();
+    (*pp)->Value = listSymPattern->currentItem()->text();
   } else if (rbUserSym->isChecked()) {
-    pp->Value = sympath;
+    (*pp)->Value = sympath;
   }
-  pp = comp->Props.next();
-  pp->Value = edtParams->text();
-  pp->display = chbShowParams->isChecked();
-  pp = comp->Props.next();
-  pp->Value = QString(pin_string);
+  pp++;
+  (*pp)->Value = edtParams->text();
+  (*pp)->display = chbShowParams->isChecked();
+  pp++;
+  (*pp)->Value = QString(pin_string);
   Doc->recreateComponent(comp);
   Doc->viewport()->repaint();
   Doc->setChanged(true,true);
diff --git a/qucs/spicecomponents/sp_nutmeg.cpp b/qucs/spicecomponents/sp_nutmeg.cpp
index 3363c3a9..3d2f92b0 100644
--- a/qucs/spicecomponents/sp_nutmeg.cpp
+++ b/qucs/spicecomponents/sp_nutmeg.cpp
@@ -85,11 +85,11 @@ QString NutmegEquation::getEquations(QString sim, QStringList &dep_vars)
     else
         match = sim.startsWith(used_sim);
     if ( match || used_sim == "all" ) {
-        Property *pp = Props.first();
-        pp = Props.next();
-        for (;pp!=0;pp=Props.next()) {
-            s += QString("let %1 = %2\n").arg(pp->Name).arg(pp->Value);
-            dep_vars.append(pp->Name);
+        auto pp = Props.begin();
+        pp++;
+        for ( ; pp != Props.end() ; ++pp) {
+            s += QString("let %1 = %2\n").arg((*pp)->Name).arg((*pp)->Value);
+          dep_vars.append((*pp)->Name);
         }
     }
     return s;