How to access local static variables and local variables inside a function from other files in C/C++ programming?

file1.c

int b=2;

void func(){
    int c=10;
    static int d=10;
    int *cp=&c;
}

main.c

#include <stdio.h>
#include <stdlib.h>
extern b;
extern *cp;

int main()
{
    int a=1;
    printf("a=%d\nb=%d\n",a,b);
    printf("c=%d\nd=%d\n",c,*cp);
    return 0;
}

I couldn't able to access local variable 'c' from other file using pointe '*cp' as well. I know by default we can access the functions from other files without using extern keyword but how to access the local variables and static variables present inside those functions ?