FREAD(3S) (C Programming Language Utilities) FREAD(3S)
NAME
fread, fwrite - binary input/output
SYNOPSIS
#include <stdio.h>
#include <sys/types.h>
int fread (ptr, size, nitems, stream)
char *ptr;
int nitems;
sizet size;
FILE *stream;
int fwrite (ptr, size, nitems, stream)
char *ptr;
int nitems;
sizet size;
FILE *stream;
DESCRIPTION
fread copies, into an array pointed to by ptr, nitems items
of data from the named input stream, where an item of data
is a sequence of bytes (not necessarily terminated by a null
byte) of length size. fread stops appending bytes if an
end-of-file or error condition is encountered while reading
stream, or if nitems items have been read. fread leaves the
file pointer in stream, if defined, pointing to the byte
following the last byte read if there is one. fread does
not change the contents of stream.
fwrite appends at most nitems items of data from the array
pointed to by ptr to the named output stream. fwrite stops
appending when it has appended nitems items of data or if an
error condition is encountered on stream. fwrite does not
change the contents of the array pointed to by ptr.
The argument size is typically sizeof(*ptr) where the
pseudo-function sizeof specifies the length of an item
pointed to by ptr. If ptr points to a data type other than
char it should be cast into a pointer to char.
Page 1 May 1989
FREAD(3S) (C Programming Language Utilities) FREAD(3S)
SEE ALSO
read(2), write(2), fopen(3S), getc(3S), gets(3S),
printf(3S), putc(3S), puts(3S), scanf(3S), stdio(3S).
DIAGNOSTICS
fread and fwrite return the number of items read or written.
If nitems is non-positive, no characters are read or written
and 0 is returned by both fread and fwrite.
Page 2 May 1989