Jan 11, 2002

Reading assignment:
  Deitel and Deitel 4.1-4.5

We begin by completing the recursion example, the towers of Hanoi.
Here's the source code for the program from class today:

Now we'll move on to arrays and strings:
   
Arrays:
  - An array is a consecutive group of memory locations storing elements
    of the same type 
  - Arrays are indexed starting at 0
  - You can gain access to individual elements of an array using square
    brackets.  For example, arr[3] accesses the 4th element of array arr.
    If you subscript an array, as in arr[3], you get an lvalue.  This
    means you can assign values to subscripted arrays, as in arr[3]=newvalue;
  - Know how to declare and define them:
    double arr[22]; or int arr[20] = {1, 2, 3};
    If there are too many initializers, it's a syntax error, if there
    are too few, the rest are set to 0
  - You can arrays of objects too, as in
    your_favorite_class obj_arr[YOUR_MAX_ARR_CONSTANT];
  - If no size is given, the size is determined by the initializer, as in
      int arr[] = {1,2,3,4,5}; defines a 5-element integer array
  - If you don't initialize in the definition, you can do it with a loop
  - Computations on arrays are typically done with loops - Examples in class
    today and on next pencil-and-paper assignment
  - To pass an array to a function, just put its name as the parameter.
    You'll probably have to pass the length of the array as well.
      Here's a prototype: void array_function_example(int b[], int arrlen);
    If you think this is yucky, you're right - it's recommended to use
    the vector class instead for a more robust system of using arrays.
    We will learn this shortly.
  - There's something a little funky about arrays when you pass them to
    functions - It's actually an automatic pass by reference - the caller
    can modify the values in the array.
  - You can protect an array that you pass to a function by declaring
    the parameter as const, as in
      void array_function_example(const int b[], int arrlen);
  - It's important to be able to sort the elements in an array and to
    find elements in an array.  There are many algorithms that have been
    invented to do this - we'll study them shortly