man : putc(3)
PUTC(3) OpenBSD Programmer's Manual PUTC(3)
fputc, putc, putchar, putw - output a character or word to a stream
fputc(int c, FILE *stream);
putc(int c, FILE *stream);
putw(int w, FILE *stream);
The fputc() function writes the character c (converted to an unsigned
char) to the output stream pointed to by stream.
putc() acts essentially identically to fputc(), but is a macro that
expands in-line. It may evaluate stream more than once, so arguments
given to putc() should not be expressions with potential side effects.
putchar() is identical to putc() with an output stream of stdout.
The putw() function writes the specified int w to the named output
The functions fputc(), putc(), and putchar() return the character
written. If an error occurs, the value EOF is returned and the global
variable errno is set to indicate the error. The putw() function returns
0 on success; EOF is returned if a write error occurs, or if an attempt
is made to write a read-only stream. The global variable errno may be
set to indicate the error.
The function putw() may also fail and set errno for any of the errors
specified for the routines write(2) or realloc(3).
ferror(3), fopen(3), getc(3), stdio(3)
The functions fputc(), putc(), and putchar(), conform to ANSI X3.159-1989
(``ANSI C''). A function putw() function appeared in Version 6 AT&T
Since the size and byte order of an int may vary from one machine to
another, putw() is not recommended for portable applications.
OpenBSD 4.9 May 31, 2007 OpenBSD 4.9