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fwrite(3p) — Linux manual page

PROLOG \|NAME \|SYNOPSIS \|DESCRIPTION \|RETURN VALUE \|ERRORS \|EXAMPLES \|APPLICATION USAGE \|RATIONALE \|FUTURE DIRECTIONS \|SEE ALSO \|COPYRIGHT

FWRITE(3P)              POSIX Programmer's ManualFWRITE(3P)

PROLOG top

       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 top

       fwrite — binary output

SYNOPSIS top

       #include <stdio.h>       size_t fwrite(const void *restrictptr, size_tsize, size_tnitems,           FILE *restrictstream);

DESCRIPTION top

       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.       Thefwrite() function shall write, from the array pointed to byptr, up tonitems elements whose size is specified bysize, to the       stream pointed to bystream.  For each object,size calls shall be       made to thefputc() function, taking the values (in order) from an       array ofunsigned charexactly 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 offwrite() and the next successful completion of a call       tofflush() orfclose() on the same stream, or a call toexit() orabort().

RETURN VALUE top

       Thefwrite() function shall return the number of elements       successfully written, which may be less thannitems if a write       error is encountered. Ifsize ornitems 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, anderrno shall be set to indicate the error.

ERRORS top

       Refer tofputc(3p).The following sections are informative.

EXAMPLES top

       None.

APPLICATION USAGE top

       Because of possible differences in element length and byte       ordering, files written usingfwrite() are application-dependent,       and possibly cannot be read usingfread() by a different       application or by the same application on a different processor.

RATIONALE top

       None.

FUTURE DIRECTIONS top

       None.

COPYRIGHT top

       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 athttp://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, seehttps://www.kernel.org/doc/man-pages/reporting_bugs.html .IEEE/The Open Group                2017FWRITE(3P)

Pages that refer to this page:stdio.h(0p)

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