I am trying to copy a file from one directory to another

Tried QFile::copy(). The file is copied but the size is zero Kb

Tried placing a dummy file and then replacing with original

But still the size is 0 Kb.

Qt Code: 
  1. QDir qd;
  2.     QFile srcfile;
  3.     QFile destifile;
  4.  
  5.     QString dbsrcfilepath = qd.currentPath().append("/learnOn1.sqlite");
  6.     dbsrcfilepath = QDir::toNativeSeparators(dbsrcfilepath);
  7.  //   dbsrcfilepath :  "/Users/user/build-learnOn-Desktop_Qt_5_4_0_clang_64bit-Debug/learnOn.app/Contents/MacOS/learnOn1.sqlite"
  8.     QString libpath = qd.homePath() + QDir::separator()+"learnOnContent" + QDir::separator();
  9.     if(!(QDir(libpath).exists()))
  10.         QDir().mkdir(libpath);
  11.     QString dbdestinationfilepath = libpath.append("learnOn.sqlite");
  12.  //dbdestinationfilepath :  "/Users/user/learnOnContent/learnOn.sqlite"
  13.  
  14.     dbdestinationfilepath = QDir::toNativeSeparators(dbdestinationfilepath);
  15.  
  16.     srcfile.setFileName(dbdestinationfilepath);
  17.     destifile.setFileName(dbsrcfilepath);
  18.     if(!srcfile.exists())
  19.     {       
  20.         bool success = true;
  21.         success &= destifile.open( QFile::ReadOnly );
  22.         success &= srcfile.open( QFile::WriteOnly | QFile::Truncate );
  23.         qDebug()<<destifile.readAll().length();
  24.         success &= srcfile.write( destifile.readAll() ) >= 0;
  25.         destifile.close();
  26.         srcfile.close();
  27.     }
  28.     else
  29.     {
  30.         srcfile.copy(dbdestinationfilepath);
  31.     }
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The copy is not proper. File size is always 0.

Kindly help to resolve this issue.

Thanks in advance