fread, fwrite

Purpose

     Performs binary input/output.

Library

     Standard I/O Library (libc.a)

Syntax

     #include <stdio.h>

     int fread ((char *) ptr, sizeof (*ptr), nitems, stream)
     int nitems;
     FILE *stream;

     int fwrite ((char *) ptr, sizeof (*ptr), nitems, stream)
     int size, nitems;
     FILE *stream;

Description

     The fread subroutine copies nitems items of data from the
     input  stream into  an  array beginning  at the  location
     pointed to by the ptr  parameter.  Each data item has the
     type *ptr.

     The fread  subroutine 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  nitems parameter
     have  been  copied.  fread  leaves  the  file pointer  of
     stream, if  defined, pointing  to the byte  following the
     last byte  read, if there  is one.  The  fread subroutine
     does not change the contents of stream.

     The fwrite subroutine appends nitems items of data of the
     type *ptr from the array  pointed to by the ptr parameter
     to the output stream.

     The  fwrite subroutine  stops writing  bytes if  an error
     condition is encountered on stream, or when the number of
     items of data specified by the nitems parameter have been
     written.  The fwrite subroutine  does not change the con-
     tents of the array pointed to by the ptr parameter.

Return Value

     The  fread and  fwrite subroutines  return the  number of
     items actually read or  written.  If the nitems parameter
     is negative or 0, no  characters are read or written, and
     a value of 0 is returned.

Related Information

     In this  book:  "read,  readx," "write,  writex," "fopen,
     freopen,  fdopen," "getc,  fgetc, getchar,  getw," "gets,
     fgets," "printf,  fprintf, sprintf,  NLprintf, NLfprintf,
     NLsprintf," "putc, putchar,  fputc, putw," "puts, fputs,"
     "scanf, fscanf, sscanf, NLscanf, NLfscanf, NLsscanf," and
     "standard i/o library."