Creates temporary file which will be removed when closed or on normal program termination.
standard mode (mode “wb+”)
Returns stream or NULL on failure.

/* 
 * tmpfile example code
 * http://code-reference.com/c/stdio.h/tmpfile 
 */
 
#include <stdio.h> /* including standard library */
//#include <windows.h> /* uncomment this for Windows */
 
 
int main ( void )
{
  FILE *stream = tmpfile();
  char c;
 
  if( stream == NULL ) {
  perror("Error opening tmp file");
 }
 
 fputs("Test 1234", stream);
 rewind(stream);
 
  while((c = fgetc(stream) ) != EOF) {
    printf("%c", c);
  }
 
 fclose (stream);
 
  return 0;
}

  output: ./tmpfile
  Test 1234