fread, fwrite − binary stream input/output


     , size_t size_t fread(void *ptr

     , size_t size_t fwrite(const void *ptr );
FILE *stream

The function reads nmemb items of data, each size bytes
long, from the stream pointed to by storing them at the
location given by

     The function writes nmemb items of data, each size
bytes long, to the stream pointed to by obtaining them from
the location given by

     For nonlocking counterparts, see

On success, and 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).

     does not distinguish between end‐of‐file and error, and
callers must use and to determine which occurred.

For an explanation of the terms used in this section, see

│Interface         Attribute     Value   │
│                  │ Thread safety MT‐Safe │

POSIX.1‐2001, POSIX.1‐2008, C89.

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