====== vfscanf ======
<code c>
int vfscanf ( FILE * stream, const char * format, va_list arg );
</code>

==== description of vfscanf ====
The vscanf(), vfscanf(), and vsscanf() functions shall be equivalent to the scanf(), fscanf(), and sscanf() functions, respectively, except that instead of being called with a variable number of arguments, they are called with an argument list as defined in the <stdarg.h> header. These functions shall not invoke the va_end macro. As these functions invoke the va_arg macro, the value of ap after the return is unspecified.

<code c>
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>

FILE *fp;

int my_vfscanf(char *fmt, ...)
{
   va_list  argptr;
   int cnt;
  
   va_start(argptr, fmt);
   cnt = vfscanf(fp, fmt, argptr);
   va_end(argptr);
   return(cnt);
}

int main(void)
{
   int inumber = 6;
   float fnumber = 7.0;
   char string[30] = "hoopy frood";

   fp = tmpfile();
   if (fp == NULL)
   {
      perror("tmpfile() call");
      exit(1);
   }

   fprintf(fp,"%d %f %s\n",inumber,fnumber,string);
   rewind(fp);

   my_vfscanf("%d %f %s", &inumber, &fnumber, string);
   printf("%d * %f = %s\n", inumber, fnumber, string);
   fclose(fp);

   return 0;
}

</code>

===== output of vfscanf c example =====
    6 * 7.000000 = hoopy