C in a Nutshell

Name

setbuf

Synopsis

Sets up I/O buffering for an open file

#include <stdio.h>
voidsetbuf( FILE * restrict fp, char * restrict buffer );

The setbuf() function is similar to setvbuf(), except that it has no return value, and no parameters to specify a buffering mode or a buffer size. The size of the buffer established by setbuf() is given by the value of the macro BUFSIZ. If the buffer argument is not a null pointer, the setbuf() call initiates fully buffered input and output for the specified file, so that the buffer is filled completely before data appears from the source or at the destination; this behavior corresponds to the buffering mode specified by the macro _IOFBF as the mode argument to setvbuf(). If the buffer argument is a null pointer, setbuf() disables all I/O buffering for the file, so that data is written and read directly.

You may call the setbuf() function only after the file has been successfully opened, and before any file I/O operations have taken place.

Example

FILE *fp = tmpfile();
unsigned char *iobuffer = malloc( BUFSIZ );
if ( iobuffer != NULL )
{setbuf( fp, iobuffer );     // Make sure temporary file is buffered.
}
/* ... now write and read the temporary file as needed ... */

See Also

setvbuf(), fflush()