OSF

NAME

fread, fwrite - Performs input/output

LIBRARY

Standard I/O Package (libc.a)

SYNOPSIS

#include <stdio.h>

size_t fread (
void ∗pointer,
size_t size,
size_t num_items,
FILE ∗stream );

size_t fwrite (
const void ∗pointer,
size_t size,
size_t num_items,
FILE ∗stream );

PARAMETERS

pointerPoints to an array. 

sizeSpecifies the size of the variable type of the array pointed to by the pointer parameter. 

num_itemsSpecifies the number of items of data. 

streamSpecifies the input or output stream. 

DESCRIPTION

The fread() function copies num_items items of data of length size from the input stream into an array beginning at the location pointed to by the pointer parameter. 

The fread() function stops copying bytes if an End-of-File or error condition is encountered while reading from the input specified by the stream parameter, or when the number of data items specified by the num_items parameter have been copied.  It leaves the file pointer of the stream parameter, if defined, pointing to the byte following the last byte read, if there is one. The fread() function does not change the contents of the stream parameter. 

The fwrite() function appends num_items items of data of length size from the array pointed to by the pointer parameter to the output stream. 

The fwrite() function stops writing bytes if an error condition is encountered on the stream, or when the number of items of data specified by the num_items parameter have been written. The fwrite() function does not change the contents of the array pointed to by the pointer parameter. 

NOTES

AES Support Level:
Full use

RETURN VALUES

Upon successful completion, the fread() and fwrite() functions return the number of items actually transferred. If the num_items parameter is negative or 0 (zero), no characters are transferred, and a value of 0 is returned.  If a read or write error occurs, the error indicator for the stream is set and errno is set to indicate the error. 

ERRORS

Refer to the reference page for the fputc() function for error codes returned by fread() and fwrite(). 

RELATED INFORMATION

Functions: fopen(3), getc(3), gets(3), printf(3), putc(3), puts(3), read(2), scanf(3), write(2)