2.9BSD/usr/man/cat3/putc.3s

PUTC(3S)            UNIX Programmer's Manual             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;

     putchar(c)

     fputc(c, stream)
     FILE *stream;

     putw(w, stream)
     FILE *stream;

DESCRIPTION
     _P_u_t_c appends the character _c to the named output _s_t_r_e_a_m.  It
     returns the character written.

     _P_u_t_c_h_a_r(_c) is defined as _p_u_t_c(_c, _s_t_d_o_u_t).

     _F_p_u_t_c behaves like _p_u_t_c, but is a genuine function rather
     than a macro.  It may be used to save on object text.

     _P_u_t_w appends word (i.e.  int) _w to the output _s_t_r_e_a_m.  It
     returns the word written.  _P_u_t_w neither assumes nor causes
     special alignment in the file.

     The standard stream _s_t_d_o_u_t is normally buffered if and only
     if the output does not refer to a terminal; this default may
     be changed by _s_e_t_b_u_f(3S).  The standard stream _s_t_d_e_r_r is by
     default unbuffered unconditionally, but use of _f_r_e_o_p_e_n (see
     _f_o_p_e_n(3S)) will cause it to become buffered; _s_e_t_b_u_f, again,
     will set the state to whatever is desired.  When an output
     stream is unbuffered information appears on the destination
     file or terminal as soon as written; when it is buffered
     many characters are saved up and written as a block.  _F_f_l_u_s_h
     (see _f_c_l_o_s_e(3S)) may be used to force the block out early.

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

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

Printed 5/17/83                                                 1

PUTC(3S)            UNIX Programmer's Manual             PUTC(3S)

BUGS
     Because it is implemented as a macro, _p_u_t_c treats a _s_t_r_e_a_m
     argument with side effects improperly.  In particular
     `putc(c, *f++);' doesn't work sensibly.

Printed 5/17/83                                                 2