putc - Man Page

put a byte on a stream


This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.


#include <stdio.h>

int putc(int c, FILE *stream);


The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the requirements described here and the ISO C standard is unintentional. This volume of POSIX.1-2017 defers to the ISO C standard.

The putc() function shall be equivalent to fputc(), except that if it is implemented as a macro it may evaluate stream more than once, so the argument should never be an expression with side-effects.

Return Value

Refer to fputc().


Refer to fputc().

The following sections are informative.



Application Usage

Since it may be implemented as a macro, putc() may treat a stream argument with side-effects incorrectly. In particular, putc(c,*f++) does not necessarily work correctly. Therefore, use of this function is not recommended in such situations; fputc() should be used instead.



Future Directions


See Also

Section 2.5, Standard I/O Streams, fputc()

The Base Definitions volume of POSIX.1-2017, <stdio.h>

Referenced By

fputc(3p), fputs(3p), fwrite(3p), getc_unlocked(3p), putchar(3p), puts(3p), stdin(3p), stdio.h(0p).

2017 IEEE/The Open Group POSIX Programmer's Manual