fread, fwrite - binary stream input/output
#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);
The function
fread() reads
nmemb items of data, each
size
bytes long, from the stream pointed to by
stream, storing them at the
location given by
ptr.
The function
fwrite() writes
nmemb items of data, each
size
bytes long, to the stream pointed to by
stream, obtaining them from the
location given by
ptr.
For nonlocking counterparts, see
unlocked_stdio(3).
On success,
fread() and
fwrite() return the number of items read
or written. This number equals the number of bytes transferred only when
size is 1. If an error occurs, or the end of the file is reached, the
return value is a short item count (or zero).
fread() does not distinguish between end-of-file and error, and callers
must use
feof(3) and
ferror(3) to determine which occurred.
For an explanation of the terms used in this section, see
attributes(7).
| Interface |
Attribute |
Value |
| fread (), fwrite () |
Thread safety |
MT-Safe |
POSIX.1-2001, POSIX.1-2008, C89.
read(2),
write(2),
feof(3),
ferror(3),
unlocked_stdio(3)