#include <stdio.h>

int im_outside = 42;

void afunction()
{
    printf("Here is an outside variable as seen from a function %i\n", im_outside);
    printf("But now I'm going to modify it\n");
    im_outside = 27;
    printf("And here it is: %i", im_outside);
    return;
}

int main (int argc, const char * argv[])
{
    printf("Here is a variable I can see: %i\n", im_outside);
    afunction();
    return 0;
}