data is not appending to the file

[sudheer]

Hello all,
i had a problem to access the file operation, when i tried to write something to the file from my GUI(designer file) then it erasing all the data exist in the file and writing only string which i entered in the LineEdit but i want to be append it to the file.
Here is my code

#include<QtCore>
#include<QtGui>
#include"ui_dialog1.h"
#include <stdio.h>
 
 
class synopsys : public QDialog,public Ui::dialog1
{
    Q_OBJECT
 
public:
    synopsys()
    {   
        setupUi(this);
       connect(pushButton1, SIGNAL(clicked()), this , SLOT(save()));
       connect(pushButton2, SIGNAL(clicked()), this , SLOT(close()));
 
    }
 
public slots:
 
  void save()
   {
     Qt::CheckState state1,state2,state3,state4;
 
     state1 = checkBox1->checkState();
     state2 = checkBox2->checkState();
     state3 = checkBox3->checkState();
     state4 = checkBox4->checkState();
 
    if(state1 == Qt::Checked)
     { 
       fileName = "/home/window1/synopsys_startup.txt";        
        QFile file(fileName);
        QString str = lineEdit1->text();
 
        const char *ch = str.toLatin1();
        file.open(QIODevice::WriteOnly);
        file.write(ch, qstrlen(ch));        
        file.close();
 
     }
 
 
 
 
     if(state2 == Qt::Checked)
     {   
 
         fileName = "/home/window1/synopsys_startup.txt";
         QFile file(fileName);
      QString str = lineEdit2->text();
 
        const char *ch = str.toLatin1();
        file.open(QIODevice::WriteOnly);
        file.write(ch, qstrlen(ch));        
        file.close();
 
 
    }
 
 
      if(state3 == Qt::Checked)
     {   
 
      fileName = "/home/window1/synopsys_startup.txt";
       QFile file(fileName);
      QString str = lineEdit3->text();
 
        const char *ch = str.toLatin1();
 
        file.open(QIODevice::WriteOnly);
        file.write(ch, qstrlen(ch));        
        file.close();
 
 
 
     }
 
 
      if(state4 == Qt::Checked)
     {   
 
       fileName = "/home/window1/synopsys_startup.txt";
       QFile file(fileName);
     QString str = lineEdit4->text();
 
        const char *ch = str.toLatin1();
        file.open(QIODevice::WriteOnly);
        file.write(ch, qstrlen(ch)); 
        file.close();
 
 
 
     }
 
 
   }
private:
     QString fileName;
 
};
 
int main(int argc, char *argv[])
{
 
     QApplication app(argc,argv);
 
      synopsys *startup = new synopsys;
      startup->show();
 
     return app.exec();
}
 
#include "main.moc"

#include<QtCore>
#include<QtGui>
#include"ui_dialog1.h"
#include <stdio.h>


class synopsys : public QDialog,public Ui::dialog1
{
    Q_OBJECT

public:
    synopsys()
    {   
        setupUi(this);
       connect(pushButton1, SIGNAL(clicked()), this , SLOT(save()));
       connect(pushButton2, SIGNAL(clicked()), this , SLOT(close()));
       
    }

public slots:

  void save()
   {
     Qt::CheckState state1,state2,state3,state4;
    
     state1 = checkBox1->checkState();
     state2 = checkBox2->checkState();
     state3 = checkBox3->checkState();
     state4 = checkBox4->checkState();
     
    if(state1 == Qt::Checked)
     { 
       fileName = "/home/window1/synopsys_startup.txt";        
        QFile file(fileName);
        QString str = lineEdit1->text();
 
        const char *ch = str.toLatin1();
        file.open(QIODevice::WriteOnly);
        file.write(ch, qstrlen(ch));        
        file.close();
        
     }

     
  

     if(state2 == Qt::Checked)
     {   
       
         fileName = "/home/window1/synopsys_startup.txt";
         QFile file(fileName);
      QString str = lineEdit2->text();
 
        const char *ch = str.toLatin1();
        file.open(QIODevice::WriteOnly);
        file.write(ch, qstrlen(ch));        
        file.close();

     
    }

    
      if(state3 == Qt::Checked)
     {   
    
      fileName = "/home/window1/synopsys_startup.txt";
       QFile file(fileName);
      QString str = lineEdit3->text();
 
        const char *ch = str.toLatin1();

        file.open(QIODevice::WriteOnly);
        file.write(ch, qstrlen(ch));        
        file.close();


 
     }

     
      if(state4 == Qt::Checked)
     {   
     
       fileName = "/home/window1/synopsys_startup.txt";
       QFile file(fileName);
     QString str = lineEdit4->text();
 
        const char *ch = str.toLatin1();
        file.open(QIODevice::WriteOnly);
        file.write(ch, qstrlen(ch)); 
        file.close();



     }

     
   }
private:
     QString fileName;
     
};

int main(int argc, char *argv[])
{
 
     QApplication app(argc,argv);
   
      synopsys *startup = new synopsys;
      startup->show();

     return app.exec();
}

#include "main.moc"

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any help or suggestion will be much appreciated