Swapping Elements in an Array

    index1 = 2;
    index2 = 4;

    // array[index1] (aka array[2]):  12
    // array[index2] (aka array[4]):  8

What if we want to swap the entries at indices 2 and 4?

    // First (incorrect) approach:
    //   Swap index1 and index2
    var temp = index1;          // temp: 2
    index1 = index2;            // index1: 4
    index2 = temp;              // index2: 2

No! We want to swap the entries __at__ indices 2 and 4!

    // Revert to original values of index1 and index2
    index1 = 2;
    index2 = 4;

    // Swap values at indices
    var temp = array[index1];          // temp: 12
    array[index1] = array[index2];     // array[index1]: 8
    array[index2 ]= temp;              // array[index2:] 12