AT&T UNIX™PC Unix System V Users Manual - tenox

FREAD ( 3S ) FREAD ( 3S )
NAME
fread, fwrite - binary input/output
SYNOPSIS
#include
int fread (ptr, size, nitems, stream)
char *ptr;
int size, niterns;
FILE *stream;
int fw rite (ptr, size, nitems, stream)
char *ptr;
int size, nitems;
FILE *stream;
DESCRIPTION
Fread copies, into an array beginning at ptr , nit ems 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 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 variable size is typically sizeof(•ptr) where the pseudofunction
size of 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.
SEE ALSO
read(2), write(2), fopen(3S), getc(3S), gets(3S), printf(3S), putc(3S),
puts(3S), scanf(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.
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