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PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
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FWRITE(3P) POSIX Programmer's Manual FWRITE(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.
fwrite — binary output
#include <stdio.h>
size_t fwrite(const void *restrict ptr, size_t size, size_t nitems,
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 fwrite() function shall write, from the array pointed to by
ptr, up to nitems elements whose size is specified by size, to
the stream pointed to by stream. For each object, size calls
shall be made to the fputc() function, taking the values (in
order) from an array of unsigned char exactly overlaying the
object. The file-position indicator for the stream (if defined)
shall be advanced by the number of bytes successfully written. If
an error occurs, the resulting value of the file-position
indicator for the stream is unspecified.
The last data modification and last file status change timestamps
of the file shall be marked for update between the successful
execution of fwrite() and the next successful completion of a
call to fflush() or fclose() on the same stream, or a call to
exit() or abort().
The fwrite() function shall return the number of elements
successfully written, which may be less than nitems if a write
error is encountered. If size or nitems is 0, fwrite() shall
return 0 and the state of the stream remains unchanged.
Otherwise, if a write error occurs, the error indicator for the
stream shall be set, and errno shall be set to indicate the
error.
Refer to fputc(3p).
The following sections are informative.
None.
Because of possible differences in element length and byte
ordering, files written using fwrite() are application-dependent,
and possibly cannot be read using fread() by a different
application or by the same application on a different processor.
None.
None.
Section 2.5, Standard I/O Streams, ferror(3p), fopen(3p),
fprintf(3p), putc(3p), puts(3p), write(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 FWRITE(3P)
Pages that refer to this page: stdio.h(0p)
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HTML rendering created 2024-06-26 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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