circularDependence

/* Here is the function declaration (aka header
 * or prototype) of `function2` */
void function2 (int a, int b);

/* Here are the function definitions */
void function1 (int c, int d)
{
    if (c < d)
        function2 (c, d);
}

void function2 (int a, int b)
{
    if (a > b)
        function1 (a, b);
}