setbuf(3p) — Linux manual page

SETBUF(3P)              POSIX Programmer's Manual             SETBUF(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

       setbuf — assign buffering to a stream

SYNOPSIS         top

       #include <stdio.h>

       void setbuf(FILE *restrict stream, char *restrict buf);

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.

       Except that it returns no value, the function call:

           setbuf(stream, buf)

       shall be equivalent to:

           setvbuf(stream, buf, _IOFBF, BUFSIZ)

       if buf is not a null pointer, or to:

           setvbuf(stream, buf, _IONBF, BUFSIZ)

       if buf is a null pointer.

RETURN VALUE         top

       The setbuf() function shall not return a value.

ERRORS         top

       Although the setvbuf() interface may set errno in defined ways,
       the value of errno after a call to setbuf() is unspecified.

       The following sections are informative.

EXAMPLES         top

       None.

APPLICATION USAGE         top

       A common source of error is allocating buffer space as an
       ``automatic'' variable in a code block, and then failing to close
       the stream in the same block.

       With setbuf(), allocating a buffer of BUFSIZ bytes does not
       necessarily imply that all of BUFSIZ bytes are used for the
       buffer area.

       Since errno is not required to be unchanged on success, in order
       to correctly detect and possibly recover from errors,
       applications should use setvbuf() instead of setbuf().

RATIONALE         top

       None.

FUTURE DIRECTIONS         top

       None.

SEE ALSO         top

       Section 2.5, Standard I/O Streams, fopen(3p), setvbuf(3p)

       The Base Definitions volume of POSIX.1‐2017, stdio.h(0p)

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 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                        SETBUF(3P)

Pages that refer to this page: stdio.h(0p),  fputc(3p),  fputwc(3p),  setvbuf(3p),  stdin(3p),  ungetc(3p),  ungetwc(3p)

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