problems

[France, stag3]

Hi all,
I work with bison and i a have trouble with it.
My grammar has no problem when my input is from the dos console but i am not 
able to read my data form a file.
I  work with the OS Windows 2000 professional and with the compiler vcc .

Here is my code :

#include <stdlib.h>

int main (int c, char **v)
{
    FILE *f;

    if ( !(f=fopen("tentative.input","r")) )
    {
        printf("%s\n","impossible ouvrir fichier dans le repertoire");
        exit(0);
        }
  select_input (f); 

  yyparse ();
}

void select_input (FILE *fin)
{
        extern FILE *yyin;
        yyin = fin;
}

Regards.
Samuel GUERIN