PUTC(3S) (C Programming Language Utilities) PUTC(3S)
NAME
putc, putchar, fputc, putw - put character or word on a
stream
SYNOPSIS
#include <stdio.h>
int putc (c, stream)
int c;
FILE *stream;
int putchar (c)
int c;
int fputc (c, stream)
int c;
FILE *stream;
int putw (w, stream)
int w;
FILE *stream;
DESCRIPTION
putc writes the character c onto the output stream (at the
position where the file pointer, if defined, is pointing).
putchar(c) is defined as putc(c, stdout). putc and putchar
are macros.
Fputc behaves like putc, but is a function rather than a
macro. Fputc runs more slowly than putc, but it takes less
space per invocation and its name can be passed as an
argument to a function.
Putw writes the word (i.e. integer) w to the output stream
(at the position at which the file pointer, if defined, is
pointing). The size of a word is the size of an integer and
varies from machine to machine. Putw neither assumes nor
causes special alignment in the file.
SEE ALSO
Page 1 May 1989
PUTC(3S) (C Programming Language Utilities) PUTC(3S)
fclose(3S), ferror(3S), fopen(3S), fread(3S), printf(3S),
puts(3S), setbuf(3S), stdio(3S).
DIAGNOSTICS
On success, these functions (with the exception of putw)
each return the value they have written. [Putw returns
ferror (stream)]. On failure, they return the constant EOF.
This will occur if the file stream is not open for writing
or if the output file cannot grow. Because EOF is a valid
integer, ferror(3S) should be used to detect putw errors.
CAVEATS
Because it is implemented as a macro, putc evaluates a
stream argument more than once. In particular, putc(c,
*f++); doesn't work sensibly. Fputc should be used instead.
Because of possible differences in word length and byte
ordering, files written using putw are machine-dependent,
and may not be read using getw on a different processor.
Page 2 May 1989