freopen in C++: Stream Redirection Guide

The freopen function in C++ is used to redirect standard input and output streams. It can be used to associate standard input/output streams with files, making it possible to redirect input/output to a file instead of the terminal.

The syntax of the function is:

FILE * freopen ( const char * filename, const char * mode, FILE * stream );

In this case, filename is the name of the file to be opened, mode is the mode in which to open the file, and stream is the stream to be redirected. It returns a pointer to the file if successful, and NULL if unsuccessful.

Using the freopen function, we can redirect the standard input stream stdin and standard output stream stdout to a file, enabling file input and output.