Utility Functions and C Language Reference > C Language Reference > Alphabetical List of Functions > fopen


Example: fopen Input-Output Functions

Opens a file for buffered I/0.

long fopen( const char *filename, const char *access_mode);

filename The name of the file to open.
access_mode The type of access mode: r, w, a or r+, w+, a+, where the "+" sign indicates that the file must already exist.

The fopen access_mode parameter serves also to specify whether we want to open the file as text or binary, adding t or b characters to this access mode string.

t Text mode. In text mode the end of file is assumed to be at first Ctrl+Z character. Some conversions can occur reading and writing with End Of Line / Feedback characters depending on your compiler and your Operating System.
b Binary mode. End of file is reached at last byte of the file. No conversions.

Return Values

If the file has been successfully opened the function will return a pointer to the file. Otherwise it returns a NULL pointer.