Laboratory: Pointers, Revisited

Summary: We continue to explore pointers, particularly the relationship between pointers and arrays.

Prerequisites: Familiarity with pointers.

• Preparation
• Exercises
  • Exercise 1: Addresses of Arrays
  • Exercise 2: Pointers and Arrays
  • Exercise 3: Arrays and Pointers, Revisited

Preparation

Finish the lab on pointers.

Exercises

Exercise 1: Addresses of Arrays

In exercise 3 of the lab on pointers, you added code to declare two arrays.

a. Add code to determine the address of element 0 of each of those arrays.

b. Add code to determine the address of element 1 of each of those arrays.

c. Add code to determine the address of element 2 of each of those arrays.

d. What do these results suggest about the organization of the arrays?

e. Add the following line to your program.

  printf ("%s: %p (%u)\n", "anthill", (void *) a, (unsigned int) a);

f. What do you expect this to print out (relative to what you printed for element 0)?

g. Check your answer experimentally.

Exercise 2: Pointers and Arrays

a. Add the following lines to your main method after the declaration of anthill.

  int *wombat = anthill;

b. What value do you expect to get when you print out wombat? (Express this relative to the value of anthill[0].)

c. Check your answer experimentally.

d. What value do you expect to get when you print out wombat + 1? (Express this relative to the value of anthill[0].)

e. Check your answer experimentally.

f. What does this suggest about adding to pointers?

Exercise 3: Arrays and Pointers, Revisited

a. Add the following code to initialize anthill.

  int i;
  for (i = 0; i < 9; i++)
    anthill[i] = i;
  anthill[9] = -1;

b. What do you expect the following code to do?

  int *wombat = anthill;
  while (*wombat >= 0)
    {
      printf ("%d\n", *wombat);
      wombat++;
    }

c. Check your answer experimentally.