open [C++ Reference]
Keywords: io,open
Date: 2009-07-15T07:34:19-0700

## open

Syntax:

        #include <fstream>
        void fstream::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 mode parameter defaults to ios::in for ifstream, ios::out for ofstream, and ios::in|ios::out for fstream. If open() fails, the stream is put into a non-good state which may be checked. For example:

       ifstream inputStream;
       inputStream.open("file.txt");

       if( !inputStream ) {
         cerr << "Error opening input stream" << endl;
       }
       // or
       if ( inputStream ) {
         // use inputStream
       }

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