Header File 

stdio.h  

Category 

Input/output Routines 

Prototype 

int vfscanf(FILE *stream, const char *format,va_list arglist); 

Description 

Scans and formats input from a stream. 

The v...scanf functions are known as alternate entry points for the ...scanf functions. They behave exactly like their ...scanf counterparts but they accept a pointer to a list of arguments instead of an argument list. 

For details on format specifiers, see Scanf Format Specifiers.  

vfscanf scans a series of input fields one character at a time reading from a stream. Then each field is formatted according to a format specifier passed to vfscanf in the format string pointed to by format. Finally vfscanf stores the formatted input at an address passed to it as an argument following format. There must be the same number of format specifiers and addresses as there are input fields. vfscanf might stop scanning a particular field before it reaches the normal end-of-field (whitespace) character or it might terminate entirely for a number of reasons. See scanf for a discussion of possible causes. 

Return Value 

vfscanf returns the number of input fields successfully scanned converted and stored; the return value does not include scanned fields that were not stored. If no fields were stored the return value is 0.  

If vfscanf attempts to read at end-of-file the return value is EOF. 

Example  

#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
FILE *fp;
int vfsf(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 = 30;
   float fnumber = 90.0;
         char string[4] = "abc";
   fp = tmpfile();
   if (fp == NULL)
   {
      perror("tmpfile() call");
      exit(1);
   }
   fprintf(fp,"%d %f %s\n",inumber,fnumber,string);
   rewind(fp);
   vfsf("%d %f %s",&inumber,&fnumber,string);
   printf("%d %f %s\n",inumber,fnumber,string);
   fclose(fp);
   return 0;
}

Portability