Answer Posted / vadivelt

It is not possible to directly access the static variable
of one file from another file. But we can access is it
in different way(by accessing the location).

Lets have a file1.c with following code:

static int a;
int *ptr = &a;/*ptr in Global scope, so by default its
storage class is extern*/

void func(void)
{
a = 30;
}

Here 'a' is static variable and it cannot be directly
accessed from another file. So create a pointer of same
data type (*ptr) and assign the address of the variable to
the pointer. Now whenever the variable value is changed in
file1.c, it will be updated in the location of 'a' and
pointer holds that location.

Now Lets have a second file with name main.c with the foll
code

#include<stdio.h>
#include<conio.h>

main()
{
extern int *ptr;
printf("%d\n", *ptr);
func();
printf("%d", *ptr);
getch();
}

Since *ptr is a extern variable and it holds the address of
a, whenever the value of the variable is changed in
file1.c, it will reflect in main.c also.

Here, when 1st printf() is executed, 'a' value would be 0.
Cos it is a static and defualt initial value is 0.

before 2nd printf() is encountered, 'a' value is changed to
30 in file1.c using func();

since we are accessing address of the variable using ptr
,the same value will reflect in main.c also.

In the same way if u want to change the value of static
variable in main.c

Just use *ptr = somevalue; it will reflect in variable 'a' in
file1.c

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