freopen() - I/O Function

freopen() is an I/O function that is used to associate an existing stream with another file. This function returns a pointer to the stream on success, a null pointer otherwise.

Syntax:

Following table lists the different modes used by this function.

Mode	Description
r	Open the text file for reading.
w	Create a text file for writing.
a	Append to a file
r+	Open a file for both reading and writing.
w+	Create a empty file for reading and writing
a+	Open a file forreading and appending.

Example :

#include <stdio.h> int main () { freopen ("freopeneg.txt","w",stdout); printf ("This text is redirected to freopeneg.txt."); fclose (stdout); return 0; }

Result :
In the above example the "freopen()" is used redirect a standard output stream to write a text.