It does not work. I have now made steg.h as
Qt Code: 
  1. #ifndef STEG_H
  2. #define STEG_H
  3. #include "ui_stegform1.h"
  4. #include <QProcess>
  5. #include <QMessageBox>
  6. class steg  : public QDialog 
  7.  {
  8.      Q_OBJECT
  9.  public:
  10.      steg(QWidget *parent = 0); 
  11.       QProcess *_proc;   
  12.     // steg(QStringList s2)
  13.       //{
  14. 	//   _proc = new QProcess( this );
  15.                // _proc->setReadChannelMode( QProcess::MergedChannels );
  16. 	// connect( _proc, SIGNAL( readyReadStandardOutput() ), this, SLOT( read()));
  17. 	// connect( _proc, SIGNAL( finished(int, QProcess::ExitStatus) ), QCoreApplication::instance(), SLOT( quit() ) );
  18. 	// _proc->start(("cjpeg"),s2);
  19.      // }
  20.  
  21. private slots:       
  22.         void stego();
  23.         void read()
  24.       	 {
  25.               QMessageBox::information( 0, "stego", _proc->readAllStandardOutput());
  26.      		 }
  27. private:
  28.      Ui::steg ui;     
  29.  };
  30. #endif
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and steg.cpp as

Qt Code: 
  1. void steg::stego()  /*** THIS MODULE  HIDES  CODED.TXT ***/
  2. {
  3. 	  if(QFile::exists("coded.txt")) 
  4. 			{  
  6. 			s2 << "-steg" << "coded.txt" << "-q" << ui.compressionspinBox->text() << "cleanimage.ppm" << ui.jpeglineEdit ->text() ;
  7. 		 	//QProcess *_proc;
  8. 			_proc = new QProcess( this );
  9. 			_proc->setReadChannelMode( QProcess::MergedChannels );
  10.  
  11. 	 		connect( _proc, SIGNAL( readyReadStandardOutput() ), this, SLOT( read()));
  12. 			// connect( _proc, SIGNAL( finished(int, QProcess::ExitStatus) ), QCoreApplication::instance(), SLOT( quit() ) );
  13. 			 _proc->start(("cjpeg"),s2);
  14. 			read();
  15. 	}
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I have to have _proc declared in steg.h since I use it in read() also.
I donot know where is the problem