setbuf
Controls stream buffering.
voidsetbuf(FILE*stream,char*buffer);
| Routine | Required Header | Compatibility |
| setbuf | <stdio.h> | ANSI, Win 95, Win NT |
For additional compatibility information, see Compatibility in the Introduction.
Libraries
| LIBC.LIB | Single thread static library, retail version |
| LIBCMT.LIB | Multithread static library, retail version |
| MSVCRT.LIB | Import library for MSVCRT.DLL, retail version |
Return Value
None
Parameters
stream
Pointer to FILE structure
buffer
User-allocated buffer
Remarks
The setbuf function controls buffering for stream. The stream argument must refer to an open file that has not been read or written. If the buffer argument is NULL, the stream is unbuffered. If not, the buffer must point to a character array of length BUFSIZ, where BUFSIZ is the buffer size as defined in STDIO.H. The user-specified buffer, instead of the default system-allocated buffer for the given stream, is used for I/O buffering. The stderr stream is unbuffered by default, but you can use setbuf to assign buffers to stderr.
setbuf has been replaced by setvbuf, which is the preferred routine for new code. setbuf is retained for compatibility with existing code.
Example
/* SETBUF.C: This program first opens files named DATA1 and
* DATA2. Then it uses setbuf to give DATA1 a user-assigned
* buffer and to change DATA2 so that it has no buffer.
*/
#include <stdio.h>
void main( void )
{
char buf[BUFSIZ];
FILE *stream1, *stream2;
if( ((stream1 = fopen( "data1", "a" )) != NULL) &&
((stream2 = fopen( "data2", "w" )) != NULL) )
{
/* "stream1" uses user-assigned buffer: */
setbuf( stream1, buf );
printf( "stream1 set to user-defined buffer at: %Fp\n", buf );
/* "stream2" is unbuffered */
setbuf( stream2, NULL );
printf( "stream2 buffering disabled\n" );
_fcloseall();
}
}
Output
stream1 set to user-defined buffer at: 0013FDA0
stream2 buffering disabled