< c‎ | io
Revision as of 22:51, 2 November 2012 by P12bot (Talk | contribs)

Defined in header <stdio.h>
FILE *fopen( const char *filename, const char *mode );

Opens a file indicated by filename and returns a file stream associated with that file. mode is used to determine the file access mode.


filename - file name to associate the file stream to
mode - null-terminated character string determining file access mode
File access
mode string
Meaning Explanation Action if file
already exists
Action if file
does not exist
"r" read Open a file for reading read from start failure to open
"w" write Create a file for writing destroy contents create new
"a" append Append to a file write to end create new
"r+" read extended Open a file for read/write read from start error
"w+" write extended Create a file for read/write destroy contents create new
"a+" append extended Open a file for read/write write to end create new
File access mode flag "b" can optionally be specified to open a file in binary mode. This flag has no effect on POSIX systems, but on Windows, for example, it disables special handling of '\n' and '\x1A'.
On the append file access modes, data is written to the end of the file regardless of the current position of the file position indicator.

Return value

Opened file stream on success, NULL on failure

See also

Template:c/io/dcl list fcloseTemplate:c/io/dcl list fflushTemplate:c/io/dcl list freopen