Section: POSIX Programmer's Manual (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.
--- assign buffering to a stream
void setbuf(FILE *restrict stream, char *restrict buf);
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.1-2008 defers to the ISO C standard.
Except that it returns no value, the function call:
shall be equivalent to:
setvbuf(stream, buf, _IOFBF, BUFSIZ)
is not a null pointer, or to:
setvbuf(stream, buf, _IONBF, BUFSIZ)
is a null pointer.
function shall not return a value.
interface may set
in defined ways, the value of
after a call to
The following sections are informative.
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
allocating a buffer of BUFSIZ bytes does not necessarily imply that all
of BUFSIZ bytes are used for the buffer area.
is not required to be unchanged on success, in order to correctly detect
and possibly recover from errors, applications should use
, Standard I/O Streams,
The Base Definitions volume of POSIX.1-2008,
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
(This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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
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