Open file ''example.dat'' for reading and writing : ostream « File Stream « C++ Tutorial






  1. C++ Tutorial
  2. File Stream
  3. ostream
/* The following code example is taken from the book
 * "The C++ Standard Library - A Tutorial and Reference"
 * by Nicolai M. Josuttis, Addison-Wesley, 1999
 *
 * (C) Copyright Nicolai M. Josuttis 1999.
 * Permission to copy, use, modify, sell and distribute this software
 * is granted provided this copyright notice appears in all copies.
 * This software is provided "as is" without express or implied
 * warranty, and with no claim as to its suitability for any purpose.
 */
#include <iostream>
#include <fstream>
using namespace std;

int main()
{
    // open file ''example.dat'' for reading and writing
    filebuf buffer;
    ostream output(&buffer);
    istream input(&buffer);
    buffer.open ("example.dat", ios::in | ios::out | ios::trunc);

    for (int i=1; i<=4; i++) {
        // write one line
        output << i << ". line" << endl;

        // print all file contents
        input.seekg(0);          // seek to the beginning
        char c;
        while (input.get(c)) {
            cout.put(c);
        }
        cout << endl;
        input.clear();           // clear  eofbit and  failbit
    }
}

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3. line

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4. line




12.11.ostream
12.11.1.Define your own ostream variable
12.11.2.file descriptor out buffer
12.11.3.stream for hexadecimal standard output
12.11.4.Switch between decimal and hexadecimal output
12.11.5.Hex out stream
12.11.6.Redirect ouput into the file
12.11.7.Open file ''example.dat'' for reading and writing