Hi,
I create new C++ class:

myxmlclass.h:
Qt Code: 
  1. #ifndef MYXMLCLASS_H
  2. #define MYXMLCLASS_H
  3.  
  4.  
  5. class MyXMLClass
  6. {
  7. public:
  8.     MyXMLClass();
  9.  
  10. public slots:
  11.     void SaveXMLFile();
  12.     void ReadXMLFile();
  13. };
  14.  
  15. #endif // MYXMLCLASS_H
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myxmlclass.cpp:
Qt Code: 
  1. #include <myxmlclass.h>
  2. #include <QFileDialog>
  3. #include <QXmlStreamWriter>
  4.  
  5. void MyXMLClass::SaveXMLFile()
  6. {
  7.  
  8.     QString filename = QFileDialog::getSaveFileName(this,
  9.                                        tr("Save Xml"), ".",
  10.                                        tr("Xml files (*.xml)"));
  11.  
  12.  
  13.     QFile file(filename);
  14.     file.open(QIODevice::WriteOnly);
  15.  
  16.     QXmlStreamWriter xmlWriter(&file);
  17.     xmlWriter.setAutoFormatting(true);
  18.     xmlWriter.writeStartDocument();
  19.  
  20.     xmlWriter.writeStartElement("LAMPS");
  21.  
  22.     xmlWriter.writeStartElement("LIGHT1");
  23.     xmlWriter.writeTextElement("State", "statevalue" );
  24.     xmlWriter.writeTextElement("Room", "roomvalue");
  25.     xmlWriter.writeTextElement("Potencial", "potencialvalue");
  26.  
  27.     xmlWriter.writeEndElement();
  28.  
  29.         file.close();
  30. }
  31.  
  32.  
  33.  
  34. void MyXMLClass::ReadXMLFile()
  35. {
  36.     QXmlStreamReader Rxml;
  37.  
  38.     QString filename = QFileDialog::getOpenFileName(this,
  39.         tr("Open Xml"), ".",
  40.         tr("Xml files (*.xml)"));
  41.  
  42.     QFile file(filename);
  43.     if (!file.open(QFile::ReadOnly | QFile::Text))
  44.     {
  45.         std::cerr << "Error: Cannot read file " << qPrintable(filename)
  46.             << ": " << qPrintable(file.errorString())
  47.             << std::endl;
  48.  
  49.     }
  50.  
  51.     Rxml.setDevice(&file);
  52.     Rxml.readNext();
  53.  
  54.     while (!Rxml.atEnd())
  55.     {
  56.         if (Rxml.isStartElement())
  57.         {
  58.             if (Rxml.name() == "LAMPS")
  59.             {
  60.                 Rxml.readNext();
  61.             }
  62.             else if (Rxml.name() == "LIGHT1")
  63.             {
  64.                 while (!Rxml.atEnd())
  65.                 {
  66.                     if (Rxml.isEndElement())
  67.                     {
  68.                         Rxml.readNext();
  69.                         break;
  70.                     }
  71.                     else if (Rxml.isCharacters())
  72.                     {
  73.                         Rxml.readNext();
  74.                     }
  75.                     else if (Rxml.isStartElement())
  76.                     {
  77.                         if (Rxml.name() == "State")
  78.                         {
  79.                             ReadStateElement();
  80.                         }
  81.                         else if (Rxml.name() == "Room")
  82.                         {
  83.                             ReadRoomElement();
  84.                         }
  85.                         else if (Rxml.name() == "Potencial")
  86.                         {
  87.                             ReadPotencialElement();
  88.                         }
  89.                         Rxml.readNext();
  90.                     }
  91.                     else
  92.                     {
  93.                         Rxml.readNext();
  94.                     }
  95.                 }
  96.             }
  97.         }
  98.         else
  99.         {
  100.             Rxml.readNext();
  101.         }
  102.  
  103.         file.close();
  104.  
  105.         if (Rxml.hasError())
  106.         {
  107.             std::cerr << "Error: Failed to parse file "
  108.                 << qPrintable(filename) << ": "
  109.                 << qPrintable(Rxml.errorString()) << std::endl;
  110.         }
  111.         else if (file.error() != QFile::NoError)
  112.         {
  113.             std::cerr << "Error: Cannot read file " << qPrintable(filename)
  114.                 << ": " << qPrintable(file.errorString())
  115.                 << std::endl;
  116.         }
  117.     }
  118. }
  119.  
  120.  
  121.  
  122. //Example for Room Element
  123.  
  124. void MyXMLClass::ReadRoomElement()
  125. {
  126.     while(!Rxml.atEnd())
  127.     {
  128.         if(Rxml.isEndElement())
  129.         {
  130.             Rxml.readNext();
  131.             break;
  132.         }
  133.         else if(Rxml.isStartElement())
  134.         {
  135.             QString roomelement = Rxml.readElementText();   //Get the xml value
  136.             Rxml.readNext();
  137.             break;
  138.         }
  139.         else if(Rxml.isCharacters())
  140.         {
  141.             Rxml.readNext();
  142.         }
  143.         else
  144.         {
  145.             Rxml.readNext();
  146.         }
  147.     }
  148.  
  149. }
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I have syntax error : missing ':' before identifier 'slots'.