NAME

puts — put a string on standard output

SYNOPSIS

#include <stdio.h>

int puts(const char *s);


DESCRIPTION

^[CX] 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.1-2024 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.

^[CX] 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, ^[CX]  and errno shall be set to indicate the error.

ERRORS

Refer to fputc.

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.1-2024 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

2.5 Standard I/O Streams, fopen, fputs, putc

XBD <stdio.h>

CHANGE HISTORY

First released in Issue 1. Derived from Issue 1 of the SVID.

Issue 6

Extensions beyond the ISO C standard are marked.

Issue 7

Changes are made related to support for finegrained timestamps.

POSIX.1-2008, Technical Corrigendum 1, XSH/TC1-2008/0476 [174,412] and XSH/TC1-2008/0477 [14] are applied.