fopen() - I/O Function

fopen() is an I/O function that used to open a file pointed by the function to return the stream associated with it.

Syntax:

In the above syntax the "mode" specifies the different modes used to open the file. Following table lists the different modes.

Mode	Description
r	Open the text file for reading.
w	Create a text file for writing.
a	Append to text file
rb	Open a binary file for reading
wb	create a bnary file for writing
ab	Append to a binary file
r+	Open a text file for read/write
w+	Create a text filefor read/write.
a+	Open a text file for read/write.
rb+ or r+b	Open a binary file for read/write.
wb+ or w+b	Create a binary file for read/write.
ab+ or a+b	Open a binary file for read/write.

Example :

#include <stdio.h> int main () { FILE * str = fopen ("fopeneg.txt","w"); fputs ("Used fopen function", str); fclose (str); return 0; }

Result:fopeneg.txt

In the above example the function is used to open the file in the write mode. Then the "fputs()" is used to write the text to the file.