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Command: fread | Section: 3 | Source: OpenBSD | File: fread.3
FREAD(3) FreeBSD Library Functions Manual FREAD(3)
NAME
fread, fwrite - binary stream input/output
SYNOPSIS
#include <stdio.h>
size_t
fread(void *ptr, size_t size, size_t nmemb, FILE *stream);
size_t
fwrite(const void *ptr, size_t size, size_t nmemb, FILE *stream);
DESCRIPTION
The function fread() reads nmemb objects, each size bytes long, from the
stream pointed to by stream, storing them at the location given by ptr.
The function fwrite() writes nmemb objects, each size bytes long, to the
stream pointed to by stream, obtaining them from the location given by
ptr.
RETURN VALUES
The functions fread() and fwrite() advance the file position indicator
for the stream by the number of bytes read or written. They return the
number of objects read or written. If size or nmemb is 0, fread() and
fwrite() return 0 with no change made to the stream. If the product of
size and nmemb results in integer overflow, 0 is returned and errno is
set to EOVERFLOW. If an error occurs, or the end-of-file is reached, the
return value is a short object count (or zero).
The function fread() does not distinguish between end-of-file and error,
and callers must use feof(3) and ferror(3) to determine which occurred.
The function fwrite() returns a value less than nmemb only if a write
error has occurred.
SEE ALSO
read(2), write(2)
STANDARDS
The functions fread() and fwrite() conform to ANSI X3.159-1989
("ANSI C89").
HISTORY
The functions fread() and fwrite() first appeared in Version 7 AT&T UNIX.
FreeBSD 14.1-RELEASE-p8 March 12, 2015 FreeBSD 14.1-RELEASE-p8