6.18.42 setvbuf Function

Defines the stream to be buffered and the buffer size.

Include

<stdio.h>

Prototype

int setvbuf(FILE * restrict stream, char * restrict buf, int mode, size_t size);

Arguments

stream

pointer to the open stream

buf

user allocated buffer

mode

type of buffering

size

size of buffer

Return Value

Returns 0 if successful

Remarks

setvbuf must be called after fopen but before any other function calls that operate on the stream. For the mode argument, use one of the following tabulated modes.

When building with MPLAB XC16 or XC-DSC, this function requires a heap.

Example

#include <stdio.h>

int main(void)
{
  FILE *myfile1, *myfile2;
  char buf[256];
  if ((myfile1 = fopen("afile1", "w+")) != NULL)
  {
    if (setvbuf(myfile1, NULL, _IONBF, 0) == 0)
      printf("myfile1 has no buffering\n");
    else
      printf("Unable to define buffer stream and/or size\n");
  }
  fclose(myfile1);
  if ((myfile2 = fopen("afile2", "w+")) != NULL)
  {
    if (setvbuf(myfile2, buf, _IOFBF, sizeof(buf)) == 0)
      printf("myfile2 has a buffer of %d characters\n", sizeof(buf));
    else
      printf("Unable to define buffer stream and/or size\n");
  }
  fclose(myfile2);
}

Example Output

myfile1 has no buffering
myfile2 has a buffer of 256 characters