How to know the size of array

Hi,

I have a question.

How can i know the size of array when it is passed to a function.
For Example i have this code:

#include <stdio.h>
#include <stdlib.h>

void foo(int * array);

int main(void)
{
int n=5;
int array[n];

foo(array);

}

void foo(int * array)
{

/*Here how can i know the size of array without passing it explicitly*/
}


Thanx in advance

Vishal

.