SETBUF(3) Library Functions Manual SETBUF(3)

setbuf — assign buffering to a stream

#include <stdio.h>

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 IEEE Std 1003.1-2001 (“POSIX.1”) 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.

The setbuf () function shall not return a value.

No errors are defined.

None.

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.

None.

None.

fopen(3), setvbuf(3), the Base Definitions volume of IEEE Std 1003.1-2001 (“POSIX.1”), <stdio.h>

First released in Issue 1. Derived from Issue 1 of the SVID.

The prototype for setbuf () is updated for alignment with the ISO/IEC 9899:1999 (“ISO C99”) standard.

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January 1, 2004 posix.fail