File Access


Opening files
Syntax
  • ifstream ifs(FILENAME, MODE);   // Input
  • ofstream ofs(FILENAME, MODE);   // Output
  • fstream fs(FILENAME, MODE);   // Input / Output
Usage
  • File mode
  • ios::in   // Input
  • ios::out   // Output
  • ios::app   // Append
  • ios::ate   // Position file at end
  • ios::trunc   // Delete file if it exists
  • ios::nocreate   // File must already exist
  • ios::noreplace   // File must not exist
  • ios::binary   // Binary file
Reading files
Examples
#include <iostream>
#include <fstream>
...
ifstream fs("input.txt", ios::in);
if (fs) {
    char ch;
    while (fs.get(ch)) {
        cout << ch;
    }
}
Writing files
Examples
#include <iostream>
#include <fstream>
...
ofstream fs("output.txt", ios::out);
if (fs) {
    fs << "This is a newly-created output file";
}