Laboratory Exercise on Function Prototypes and the Run-time Stack

Function Prototypes

1. Program add2.c utilizes a function prototype at the start of the code for function add2, followed by the main procedure and then the complete function definition for add2.

   1. Copy program add2.c to your account, compile it, run it, and write a brief description of how it works.
   2. Comment out the function prototype for add2 at the beginning of the program, and then try to compile the program again. Describe what happens and explain why.
   3. Going back to the original program, change the prototype so the parameter value has type int. (Do not change the function definition at the bottom of the code!) Again, try to compile the program, describe what happens, and explain why.

2. Copy the simulation program couple-6.c to your account.

   1. Modify the program so that functions simulate_couple and simulate_several_couples are defined in full at the end of the file — that is, after main is defined. Try to compile and run the program and explain what happens.
   2. Building on part a, add an index of functions at the start of couple-6.c, so that each function has a brief description and a function prototype. Again compile and run the program.

3. Write a program that instructs a Scribbler 2 robot to beep twice with these commands:

   rBeep (1, 880);
   rBeep (2, 1760);
   

   1. Try compiling your program without including MyroC.h.
   2. Add #include "MyroC.h" near the start of the program, and try compiling and running the program again.

   In each case, explain what happens.

The Run-time Stack

4. Returning to the original couple-6.c program, draw schematic memory diagrams for the state of memory just after each function begins and just before each function ends. Be sure you can explain the running of the program at each step, based upon this series of schematic diagrams.

5. Consider the program lab-value-param.c.

   1. Copy the program to your account, compile, and run it.

   2. Draw schematic memory diagrams for the state of memory when each print statement is executed. Be sure you can explain the running of the program at each step, based upon this series of schematic memory diagrams.

Homework

6. Write your own program to control a Scribbler 2 program.

   1. The program should command the robot to beep and/or move.
   2. The program should include these features:
      • The program should contain at least two global variables.
      • The program should have at least two functions, and each function should have both parameters and local variables.
      • At least one function should call another function.
   3. Once the program is written, draw schematic memory diagrams that shows the state of memory just after each function begins and just before each function ends.

7. Repeat Step 5 for the program homework-value-param.c.