Change the buffering scheme for a stream.

This function is compatible with the following targets:

ANSI

BeOS

EMB/RTOS

Mac OS

Palm OS

Win32

#include <stdio.h>

int setvbuf(FILE *stream, char *buf, int mode, 

Parameters for this facility are:

stream	FILE *	A pointer to a FILE stream
buf	char *	A buffer for input and output
mode	int	A buffering mode
size	size_t	The size of the buffer

The setvbuf() allows the manipulation of the buffering scheme as well as the size of the buffer used by stream. The function should be called after the stream is opened but before it is written to or read from.

The buf argument is a pointer to a character array. The size argument indicates the size of the character array pointed to by buf. The most efficient buffer size is a multiple of BUFSIZ, defined in stdio.h.

If buf is a null pointer, then the operating system creates its own buffer of size bytes.

The mode argument specifies the buffering scheme to be used with stream. mode can have one of three values defined in stdio.h: _IOFBF, _IOLBF, and _IONBF.

• _IOFBF specifies that stream be buffered.
• _IOLBF specifies that stream be line buffered.
• _IONBF specifies that stream be unbuffered
Return:

"setbuf"

"malloc"

#include <stdio.h>
#include <stdlib.h>

int main(void)
{
	FILE *f;
	char name[80];
	
	// get a filename from the user
	printf("Enter the name of the file to write to.\n");
	gets(name);

	// create a new file for output
	if ( (f = fopen(name, "w")) == NULL) {
		printf("Can't open file %s.\n", name);
		exit(1);
	}

	setvbuf(f, NULL, _IOLBF, 0);	// line buffering
	fprintf(f, "This file is now\n");
	fprintf(f, "line buffered.\n");

	// close the file
	fclose(f);

	return 0;
}
Output:
Enter the name of the file to write to.
buffy





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Last updated: August 16, 2000