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PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
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FPUTS(3P) POSIX Programmer's Manual FPUTS(3P)
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.
fputs — put a string on a stream
#include <stdio.h>
int fputs(const char *restrict s, FILE *restrict 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 fputs() function shall write the null-terminated string
pointed to by s to the stream pointed to by stream. 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 fputs() and the next successful completion of a call
to fflush() or fclose() on the same stream or a call to exit() or
abort().
Upon successful completion, fputs() shall return a non-negative
number. Otherwise, it shall return EOF, set an error indicator for
the stream, and set errno to indicate the error.
Refer to fputc(3p).
The following sections are informative.
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 fputs(). 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 ");
fputs(asctime(localtime(&now)), stdout);
printf("There are still %d minutes to the event.\n",
minutes_to_event);
...
The puts() function appends a <newline> while fputs() 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.
The fputs() function is one whose source code was specified in the
referenced The C Programming Language. In the original edition,
the function had no defined return value, yet many practical
implementations would, as a side-effect, return the value of the
last character written as that was the value remaining in the
accumulator used as a return value. In the second edition of the
book, either the fixed value 0 or EOF would be returned depending
upon the return value of ferror(); however, for compatibility with
extant implementations, several implementations would, upon
success, return a positive value representing the last byte
written.
None.
Section 2.5, Standard I/O Streams, fopen(3p), putc(3p), puts(3p)
The Base Definitions volume of POSIX.1‐2017, stdio.h(0p)
Portions of this text are reprinted and reproduced in electronic
form from IEEE Std 1003.1-2017, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The
Open Group Base Specifications Issue 7, 2018 Edition, Copyright
(C) 2018 by the Institute of Electrical and Electronics Engineers,
Inc and The Open Group. 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.opengroup.org/unix/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 .
IEEE/The Open Group 2017 FPUTS(3P)
Pages that refer to this page: stdio.h(0p), puts(3p)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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