C Pocket Reference

General File Access Functions

The following functions, macros, and symbolic constants are declared in the header file stdio.h . In the descriptions below, fp designates the file pointer. Functions with type int return 0 to indicate success, or a value other than 0 in case of errors.

void clearerr( FILE *fp );

Clears the error and end-of-file flags.

int fclose( FILE *fp );

Closes the file.

int feof( FILE *fp );

Tests whether the end of the file has been reached. Returns a value not equal to 0 if the end-of-file flag is set, or 0 if it is not.

int ferror( FILE *fp );

Tests whether an error occurred during file access. Returns a value not equal to 0 if the error flag is set, or 0 if it is not.

int fflush( FILE *fp );

Causes any unwritten data in the file buffer to be written to the file. Returns EOF if an error occurs, or 0 on success.

int fgetpos( FILE *fp, fpos_t *ppos);

Determines the current file position and copies it to the variable addressed by ppos. The type fpos_t is generally defined as long.

FILE *fopen( const char *name, const char *mode );

Opens the file name with the access mode mode. Possible access mode strings are "r" (read), "r+" (read and write), "w" (write), "w+" (write and read), "a" (append), and "a+" (append and read). For modes "r" and "r+", the file must already exist. Modes "w" and "w+" create a new file, or erase the contents of an existing file. Text or binary access mode can be specified by appending t or b to the mode string. If ...