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.1-2017 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(3) or
fclose(3) on the same stream or a call to
exit(3) or abort(3).
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(3).
EXAMPLES
Printing to Standard Output
The following example gets the current time, converts it to a
string using localtime(3) and
asctime(3), 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(3) does not.
This volume of POSIX.1-2017 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
V2_chap02(3), fopen(3), fputs(3), putc(3)
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.