5 Functions for All Subtasks

1. 5.1 void Functions 252

   1. Definitions of void Functions 252

   2. Programming Example: Converting Temperatures 255

   3. return Statements in void Functions 255

2. 5.2 Call-By-Reference Parameters 259

   1. A First View of Call-by-Reference 259

   2. Call-by-Reference in Detail 262

   3. Programming Example: The swapValues Function 267

   4. Mixed Parameter Lists 268

   5. Programming Tip: What Kind of Parameter to Use 269

   6. Pitfall: Inadvertent Local Variables 270

3. 5.3 Using Procedural Abstraction 273

   1. Functions Calling Functions 273

   2. Preconditions and Postconditions 275

   3. Case Study: Supermarket Pricing 276

4. 5.4 Testing and Debugging Functions 281

   1. Stubs and Drivers 282

5. 5.5 General Debugging Techniques 287

   1. Keep an Open Mind 287

   2. Check Common Errors 287

   3. Localize the Error 288

   4. The assert Macro 290

1. Chapter Summary 292

2. Answers to Self-Test Exercises 293

3. Practice Programs 296

4. Programming Projects 299

Everything is possible.

COMMON MAXIM

Introduction

The top-down design strategy discussed in Chapter 4 is an effective way to design an algorithm for a program. You divide the program’s task into subtasks and then implement the algorithms for these subtasks as functions. Thus far, we have seen how to define functions that start with the values of some arguments and return a single value as the result of the function call. A subtask that computes a single value is a very important kind of subtask, but it is not the only kind. In this chapter we will complete our description of C++ functions and present techniques for designing functions that perform other kinds of subtasks.

Prerequisites

You should read Chapters 2 through 4 before reading this chapter.