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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.
NAME
puts — put a string on standard output
SYNOPSIS
#include <stdio.h> int puts(const char *s);
DESCRIPTION
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.1‐2008 defers to the ISO C standard.
The puts() function shall write the string pointed to by s, followed by a <newline>, to the standard
output stream stdout. The terminating null byte shall not be written.
The last data modification and last file status change timestamps of the file shall be marked for update
between the successful execution of puts() and the next successful completion of a call to fflush() or
fclose() on the same stream or a call to exit() or abort().
RETURN VALUE
Upon successful completion, puts() shall return a non-negative number. Otherwise, it shall return EOF,
shall set an error indicator for the stream, and errno shall be set to indicate the error.
ERRORS
Refer to fputc().
The following sections are informative.
EXAMPLES
Printing to Standard Output
The following example gets the current time, converts it to a string using localtime() and asctime(), and
prints it to standard output using puts(). It then prints the number of minutes to an event for which it
is waiting.
#include <time.h>
#include <stdio.h>
...
time_t now;
int minutes_to_event;
...
time(&now);
printf("The time is ");
puts(asctime(localtime(&now)));
printf("There are %d minutes to the event.\n",
minutes_to_event);
...
APPLICATION USAGE
The puts() function appends a <newline>, while fputs() does not.
This volume of POSIX.1‐2008 requires that successful completion simply return a non-negative integer.
There are at least three known different implementation conventions for this requirement:
* Return a constant value.
* Return the last character written.
* Return the number of bytes written. Note that this implementation convention cannot be adhered to for
strings longer than {INT_MAX} bytes as the value would not be representable in the return type of the
function. For backwards compatibility, implementations can return the number of bytes for strings of
up to {INT_MAX} bytes, and return {INT_MAX} for all longer strings.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSO
Section 2.5, Standard I/O Streams, fopen(), fputs(), putc()
The Base Definitions volume of POSIX.1‐2008, <stdio.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2013 Edition,
Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of Electrical and Electronics Engineers, Inc
and The Open Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the event
of any discrepancy between this version and the original IEEE and The Open Group Standard, the original
IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at
http://www.unix.org/online.html .
Any typographical or formatting errors that appear in this page are most likely to have been introduced
during the conversion of the source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .