io:open

Syntax:

    #include <fstream>
    void open( const char *filename );
    void open( const char *filename, openmode mode = default_mode );

The function open() is used with file streams. It opens filename and associates it with the current stream. The optional io_stream_mode_flag mode defaults to ios::in for ifstream, ios::out for ofstream, and ios::in|ios::out for fstream. If open() fails, the resulting stream will evaluate to false when used in a Boolean expression. For example:

   ifstream inputStream;
   inputStream.open("file.txt");
   if( !inputStream ) {
     cerr << "Error opening input stream" << endl;
     return;
   }

Related Topics: I/O Constructors, close, C++ I/O Mode Flags