int putc (c, stream)
fputc (c, stream)
putw (w, stream)
putchar(c) is defined as putc(c, stdout).
fputc behaves like putc, but is a genuine function rather than a macro; it may therefore be used as an argument. fputc runs more slowly than putc, but takes less space per invocation.
putw appends word (i.e., int ) w to the output stream. putw neither assumes nor causes special alignment in the file.
The standard stream stdout is normally buffered if and only if the output does not refer to a terminal; this default may be changed by setbuf(3P). The standard stream stderr is by default unbuffered unconditionally, but use of freopen see ( fopen(3P) will cause it to become unbuffered; setbuf, again, will set the state to whatever is desirerd. When an output stream is unbuffered information appears on the destination file or a terminal as soon as written; when it is buffered many characters are saved up and written as a block. See also fflush in fclose(3P).