c++ file IO

This is a discussion on c++ file IO within the C++ Programming forums, part of the General Programming Boards category; Code: #include <iostream> #include <fstream> using namespace std; int main() { char c; ofstream fout("O.TXT",ios::out|ios::binary); fout << "C++Programming"; fout.close(); ifstream ...

  1. #1
    Anirban Ghosh
    Join Date
    Jan 2006
    Posts
    278

    c++ file IO

    Code:
    #include <iostream>
    #include <fstream>
    using namespace std;
    
    int main()
    {
         char c;
         
         ofstream fout("O.TXT",ios::out|ios::binary);
         fout << "C++Programming";
         fout.close();
         
         ifstream fin("O.TXT",ios::in|ios::binary); 
         while( !fin.eof() )
         {
             fin.get(c);
             if( !fin.eof() )
                 cout << c;
         }
         fin.seekg(0,ios::beg);
              
         fin.get(c);
         cout << ' ' << c << endl; 
                
         fin.close();
    
         system("PAUSE");
         return 0;
    }
    The code must give the output "C++Programming C". But the output i am getting is "C++Programming g". In many cases i have seen when i have forwarded the file pointer , the characters can be well read but when the pointer is brought back the desired characters cannot be read.

    Tried on VC++ 6.0 and DEV C++ 4.9.9.0

  2. #2
    and the hat of wrongness Salem's Avatar
    Join Date
    Aug 2001
    Location
    The edge of the known universe
    Posts
    32,558
    Because it still thinks you're at eof, so the next get call doesn't actually update c, and it's left with the last character which was successfully read.

    fin.clear(); // make the eof condition go away
    fin.seekg(0,ios::beg); // back to start

    Now I get
    $ ./a.out
    C++Programming C

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