ofstream f1("h1.txt",ios::app|ios::out);
if (!f1)
{
    cerr<<"cannot open the filen";
    exit(-1);
}
currentPos = f1.tellp();
cout<<"Initial Write Pointer Position = "<<currentPos<<endl;
// Write some data at the end
for(int index=0;index<20;index++)
{
   f1<<index;
}

currentPos= f1.tellp();

cout<<"Write Pointer Position after write = "<<currentPos<<endl;
f1.seekp(10);
currentPos= f1.tellp();
cout<<"Write Pointer Position after seek = "<<currentPos<<endl;

/** Note: Even if you reposition pointer, in app mode, data will always be written to the end */
f1<<11;
currentPos= f1.tellp();

/** seekp does not match. In app mode, data is writtten to end */
cout<<"Final Write Pointer Position after seek and write = "<<currentPos<<endl;
f1.close();