setbuf Function

Defines how a stream is buffered.

Include

<stdio.h>

Prototype

void setbuf(FILE *stream, char *buf);

Arguments

Remarks

setbuf must be called after fopen but before any other function calls that operate on the stream. If buf is a null pointer, setbuf calls the function setvbuf(stream, 0, _IONBF, BUFSIZ) for no buffering; otherwise setbuf calls setvbuf(stream, buf, _IOFBF, BUFSIZ) for full buffering with a buffer of size BUFSIZ. See setvbuf.

This function requires a heap.

Example

#include <stdio.h> /* for setbuf, printf, */
                   /* fopen, fclose,      */
                   /* FILE, NULL, BUFSIZ  */

int main(void)
{
  FILE *myfile1, *myfile2;
  char buf[BUFSIZ];

  if ((myfile1 = fopen("afile1", "w+")) != NULL)
  {
    setbuf(myfile1, NULL);
    printf("myfile1 has no buffering\n");
    fclose(myfile1);
  }

  if ((myfile2 = fopen("afile2", "w+")) != NULL)
  {
    setbuf(myfile2, buf);
    printf("myfile2 has full buffering");
    fclose(myfile2);
  }

}

Example Output

myfile1 has no buffering
myfile2 has full buffering

This macro is used by the function setbuf.