C Pocket Reference

File Input/Output Functions

The classic functions for reading from and writing to files are declared in the header file stdio.h . In the descriptions that follow in Table 1-23, fp designates the file pointer. Those functions that have no parameter with the file pointer type read from stdin or write to stdout.

Reading and writing characters and strings

Table 1-23.  Character read and write functions

Purpose	Functions
Write a character	int fputc( int c, FILE *fp ); int putc( int c, FILE *fp ); int putchar( int c );
Read a character	int fgetc( FILE *fp ); int getc( FILE *fp ); int getchar( void );
Put back a character	int ungetc( int c, FILE *fp );
Write a line	int fputs( const char *s, FILE *fp ); int puts( const char *s );
Read a line	char *fgets( char *s, int n, FILE *fp ); char *gets( char *buffer );

For each of these input/output functions, there is also a corresponding function for wide-oriented access. The wide functions are declared in the header file wchar.h ^(*). Their names are formed with wc (for wide character) in place of c (for character), or with ws (for wide string) in place of s (for string).

Block read and write functions

The following file access functions can be used to read or write a block of characters:

size_t fwrite( const void *buf, size_t sz, size_t n, FILE *fp );

Writes n objects of length sz from the buffer addressed by buf to the file.

size_t fread( void *buffer, size_t sz, size_t n, FILE *fp );

Reads up to n objects of ...