#include <iostream>
using namespace std;

// Each function "stands alone"
//   All variables are in their own scope
//   (i.e. the scope of function1)
// function1 only has a, c, and d as
//   variables in its scope
int function1( int c, int d )
{
    // memory ==>         c: 6   d: 5
    int a = 6;   //         a: 6
    c = d + a;   //       c: 11   d: 5
    d = c;       //       c: 11   d: 11
      // changing the values of c and d
      //   do NOT change any variable in main()

    return d;   // return the value of d (i.e. 11)
}

int function2( int e, int f )
{                  // e: 5    f: 11
    e = f * e;     // e: 55   f: 11
    f = e * 6;     // e: 55   f: 330
    return e;      // return 55
}

int main()
{
    // memory ==>             a: 2     b: 5
    int a = 2, b = 5;
    int g = function1( a+4, b );   //  g: 11
      // values a+4 and b (i.e. 6 and 5)
      //   are "passed by value" to function1
    cout << a << " and " << b << " and " << g << endl;

    a = function2( b, g );
    cout << a << " and " << b << " and " << g << endl;
      // ==>  55 and 5 and 11

    return 0;
}