freopen function(Reopen File) in C Language – example and detail

In the C Programming Language, the freopen characteristic first closes the file related with stream. Then the freopen function opens filename and associates it with stream. In essence, it associates a unique file to a flow that is already open.


The syntax for the fopen function in the C Language is:

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

Parameters or Arguments

filename The filename to associate with the file being reopened. mode The mode in which to open the file. stream The stream to accomplice with filename.


The freopen function returns a file pointer for the opened file. If the file can not be opened, the freopen feature returns a null pointer.

Required Header

In the C Language, the required header for the freopen feature is:

#include <stdio.h>

Applies To

In the C Language, the freopen feature can be used in the following versions:

ANSI/ISO 9899-1990

Similar Functions

Other C features that are similar to the freopen function:

fopen function <stdio.h>

See Also

Other C functions that are noteworthy when dealing with the freopen function:

fclose characteristic setbuf feature setvbuf feature