bsd man page for putchar

PUTC(3S)																  PUTC(3S)

NAME
       putc, putchar, fputc, putw - put character or word on a stream

SYNOPSIS
       #include <stdio.h>

       int putc(c, stream)
       char c;
       FILE *stream;

       int putchar(c)

       int fputc(c, stream)
       FILE *stream;

       int putw(w, stream)
       FILE *stream;

DESCRIPTION
       Putc appends the character c to the named output stream.  It returns the character written.

       Putchar(c) is defined as putc(c, stdout).

       Fputc behaves like putc, but is a genuine function rather than a macro.

       Putw  appends  word (that is, int) w to the output stream.  It returns the word written.  Putw neither assumes nor causes special alignment
       in the file.

SEE ALSO
       fopen(3S), fclose(3S), getc(3S), puts(3S), printf(3S), fread(3S)

DIAGNOSTICS
       These functions return the constant EOF upon error.  Since this is a good integer, ferror(3S) should be used to detect putw errors.

BUGS
       Because it is implemented as a macro, putc treats a stream argument with side effects improperly.  In particular

       putc(c, *f++);

       doesn't work sensibly.

       Errors can occur long after the call to putc.

7th Edition							 November 6, 1985							  PUTC(3S)