Question

// File: foo.c

static int var;

void foo()
{
var++;
}

// end of file foo.c

// File bar.c:

static int var;

void bar()
{
var++;
}

// end of file bar.c

// file main.c

static int var;
void main()
{
foo();
bar();
printf("%d", var);
}

// end of file main.c

Question: Will the above program compile ? If so what will be the result ?

I tested the code and found it couldn’t be compiled. I try to use extern in main.c to use the function foo() and bar() but it still couldn’t be compiled.

Answer 1

main.c has a few minor problems – it should be something like this:

#include <stdio.h>

static int var;

extern void foo();
extern void bar();

int main(void)
{
    foo();
    bar();
    printf("%d\n", var);
    return 0;
}

It should build OK like this:

$ gcc -Wall main.c foo.c bar.c -o main

and the result should be:

$ ./main
0