C++ Programming for Non-C Programmers. Supplement

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1 C++ Programming for Non-C Programmers Supplement

2 ii C++ Programming for Non-C Programmers C++ Programming for Non-C Programmers Published by itcourseware, E. Dry Creek Rd., Suite 150, Englewood, CO Contributing Authors: Jeff Howell, Danielle Waleri Editor: Danielle Waleri Special thanks to: Many instructors whose ideas and careful review have contributed to the quality of this workbook, including Evans Nash, and the many students who have offered comments, suggestions, criticisms, and insights. Copyright 1998 by itcourseware, Inc. All rights reserved. No part of this book may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, or by an information storage retrieval system, without permission in writing from the publisher. Inquiries should be addressed to itcourseware, Inc., E. Dry Creek Rd., Suite 150, Englewood, Colorado, (303) All brand names, product names, trademarks, and registered trademarks are the property of their respective owners.

3 Table of Contents iii Contents Chapter 1 - Course Introduction... 7 Course Objectives... 9 Course Overview Chapter 2 - Getting Started Chapter Objectives The First Program (hello.cpp) Compile Steps How to Compile and Run a Program Exercises Chapter 3 - Data Types and Variables Chapter Objectives Fundamental Data Types Data Type Values and Sizes Data Type Values and Sizes Variable Declarations Variable names Constants Character Constants String Constants Exercises Chapter 4 - Operators and Expressions Chapter Objectives What are expressions? Arithmetic Operators Relational Operators Assignment Operator Expressions have resulting values True and False Logical Operators Increment and Decrement Operators (++ and --) Increment and Decrement Operators: Examples 'Operate-Assign' Operators (+=, *=,...) Conditional Expression Operator Precedence Precedence and order of evaluation... 75

4 iv C++ Programming for Non-C Programmers Evaluation of Logical Operators Type Conversions Type conversions (cont.) The cast operator Exercises Chapter 5 - Control Flow Chapter Objectives Statements if - else if() - else if() switch() Example: Switch() switch() (cont.) while() do - while() for() The for() loop - diagram Example: for() loop The break statement The continue statement Exercises Chapter 6 - Functions Chapter Objectives What is a function? Example: findbig3() Why use functions? Anatomy of a function Example: find_big_int() Arguments passed by value When to Use the return Statement Returning Non-integer Values Example: Returning Non-integer Values Functions in Multiple Source Files The Concept of Variable Scope Automatic Variables Global (external) variables Example: Global Variables Static Variables External Static Variables Exercises

5 Table of Contents v Chapter 7 - Pointers and Arrays Chapter Objectives What is a pointer? Pointer Operators Example: pointers Why use pointers? Example Arrays: Arrays (a picture) The & Operator Pointers and arrays Passing arrays to functions Initializing arrays Strings and character pointers What is char s[7]??? Arrays of pointers Arrays of pointers - diagram Command-line arguments Exercises Chapter 8 - Structures Chapter Objectives Comparison of structures and arrays Structure definitions Structure declarations Arrays of structures Exercises

6 vi C++ Programming for Non-C Programmers

7 Chapter 1 Course Introduction 7 Chapter 1 - Course Introduction

8 8 C++ Programming for Non-C Programmers Notes

9 Chapter 1 Course Introduction 9 Course Objectives Write applications using the C++ programming language. Use all of the basic syntax and semantics of the C and C++ languages. Write modular programs using functions. Use pointers and arrays to maintain data. Create classes that represent real-world objects with data and functionality. Inherit classes from existing classes to gain a reuse of functionality. Properly use references and constants to maintain data integrity and minimize errors. Write your own operators to work with the new data types that you create. Create template classes to avoid redundant coding and increase code reuse. Program object-oriented applications of moderate complexity.

10 10 C++ Programming for Non-C Programmers Notes

11 Chapter 1 Course Introduction 11 Course Overview Audience: This course is designed for programmers who want to move from procedural thinking to object-oriented programming using C++. Prerequisites: This course assumes that the student is an experienced professional programmer. Student Materials: Student workbook. A C++ text. Reference sheets. Classroom Environment: One terminal per student using the UNIX operating system, or a PC with a current C++ compiler.

12 12 C++ Programming for Non-C Programmers Notes

13 Chapter 2 Getting Started 13 Chapter 2 - Getting Started

14 14 C++ Programming for Non-C Programmers Notes

15 Chapter 2 Getting Started 15 Chapter Objectives Compile and run a program. Become familiar with your environment. Get "hands on" the machine immediately.

16 16 C++ Programming for Non-C Programmers Notes The following line: using namespace std ; is neccessary when including standard header files, like iostream. It will be discussed later in the course.

17 Chapter 2 Getting Started 17 The First Program (hello.cpp) /* hello.cpp */ #include <iostream> using namespace std ; int main(void) { cout << "hello, world" << endl; return 0; } /* int main(void) */

18 18 C++ Programming for Non-C Programmers Notes

19 Chapter 2 Getting Started 19 Compile Steps The source code file is the file that you create with an editor. The compiler compiles the source into an object file from which the linker creates an executable file. hello.cpp Source Code File hello.o Compile Object Code File hello Link Executable Binary File

20 20 C++ Programming for Non-C Programmers Notes

21 Chapter 2 Getting Started 21 How to Compile and Run a Program The linker needs to know the names of all of the object files that are part of your executable program. On a Unix platform, you create a makefile that contains the names of all of your files, then run the utility called make which compiles and links your code. In an Integrated Development Environment (IDE) such as Borland C++ or Microsoft Visual C++, you create a project that contains the names of all of your files, then running your program will first cause it to be compiled and linked.

22 22 C++ Programming for Non-C Programmers Notes

23 Chapter 2 Getting Started 23 Exercises 1. Edit hello.cpp such that it does not print the endl. Compile and run it. 2. Edit your solution so that it uses a second cout statement to print the endl. 3. Finally, have it print hello followed by your name.

24 24 C++ Programming for Non-C Programmers Notes

25 Chapter 6 Functions 119 Chapter 6 - Functions

26 120 C++ Programming for Non-C Programmers Notes

27 Chapter 6 Functions 121 Chapter Objectives Understand the use of functions in program structure. Write modular programs consisting of functions. Pass data to functions by value and by reference. "Build" a program from multiple source files. Initialize variables at definition time. Understand the scope of variables. Know when to use global variables.

28 122 C++ Programming for Non-C Programmers Notes

29 Chapter 6 Functions 123 What is a function? A function is a set of instructions. A function may operate on data passed to it. A program "calls" a function, passing it data, if required. A function can be called with different data and from different places. A function can "return" data to its caller.

30 124 C++ Programming for Non-C Programmers Notes

31 Chapter 6 Functions 125 Example: findbig3() /* findbig3.cpp */ #include <iostream> using namespace std ; int find_big_3(int, int, int); int main(void) { int x,y,z; int largest; x = 10; y = 15; z = 12; largest = find_big_3(x, y, z); cout << "Largest: " << largest << endl; return 0; } /* int main(void) */ /* --- Function find_big_3 --- */ int find_big_3(int a, int b, int c) { int big; big = a > b? a : b; /* Bigger of a and b */ big = big > c? big : c; /* Bigger of big and c */ return big; } /* int find_big_3(int a, int b, int c) */

32 126 C++ Programming for Non-C Programmers Notes

33 Chapter 6 Functions 127 Why use functions? To design a program into modules. To perform the same instructions on different sets of data. To create a library of reusable tools.

34 128 C++ Programming for Non-C Programmers Notes

35 Chapter 6 Functions 129 Anatomy of a function void main(void) { int arg1; float arg2; char arg3; func(arg1, arg2, arg3); /* Three arguments passed */ func(100, , 'X'); /* Constants as arguments */ } /* void main(void) */ /* Function returns a float, takes three parameters */ float func(int p1, float p2, char p3) /* Arguments in calls to func agree with */ /* parameters in number and type. */ /* They need not be of same name. */ {... define any needed local variables... operate on parameters... calculate a result (the function s "return value") return 3.14F; }/* float func(int p1, float p2, char p3) */

36 130 C++ Programming for Non-C Programmers Notes

37 Chapter 6 Functions 131 Example: find_big_int() /* findbigi.cpp */ #include <iostream> using namespace std ; int find_big_int(int [], int); int main(void) { int a[5]; a[0] = 985; a[1] = 255; a[2] = 868; a[3] = 1105;; a[4] = 499; cout << "Biggest: " << find_big_int(a, 5) << endl; return 0; } /* int main(void) */ /* --- Function find_big_int --- */ int find_big_int(int a[], int num_elem) /* int a[] - Tells compiler that a is an array */ /* int num_elem - Size of array passed in */ { int i; /* Automatic local variables */ int big; big = a[0]; /* To start, assume first element is biggest */ cout << big << endl; for (i = 1; i < num_elem; i++) if (a[i] > big) { /* If i'th element is bigger, */ big = a[i]; /* then update big holder */ cout << big << endl; } return big; } /* int find_big_int(int a[], int num_elem) */

38 132 C++ Programming for Non-C Programmers Notes

39 Chapter 6 Functions 133 Arguments passed by value The data passed to a function are copies of the caller's actual data. Functions can use passed in variables, but can't change them. /* passval.cpp */ #include <iostream> using namespace std ; int passval(int); int main(void) { int x; x=99; cout << "x before call: " << x << endl; passval(x); cout << "x after call: " << x << endl; return 0; } /* int main(void) */ /* --- Function passval --- */ int passval(int a) { a = a * 10; return a; } /* int passval(int a) */ Program will print: x before call: 99 x after call: 99

40 134 C++ Programming for Non-C Programmers Notes

41 Chapter 6 Functions 135 When to Use the return Statement Typically, use return when the function calculates and returns a single value. Use pass-by-reference when multiple values will be returned. In the second case, maybe you need more than one function.

42 136 C++ Programming for Non-C Programmers Notes

43 Chapter 6 Functions 137 Returning Non-integer Values By default, functions are assumed to return type int. If return value type is non-int, there must be two declarations: 1. The function type must be declared. 2. The calling function must declare the called function (usually in a prototype).

44 138 C++ Programming for Non-C Programmers Notes

45 Chapter 6 Functions 139 Example: Returning Non-integer Values /* max3.cpp */ #include <iostream> using namespace std ; int main(void) { float one, two,three, big, max3(float, float, float); cout << "Enter three float values: "; cin >> one >> two >> three; big = max3(one, two, three); cout << "Big = " << big << endl; return 0; } /* int main(void) */ float max3(float a, float b, float c) { float big; big = a > b? a : b ; big = big > c? big : c ; return big; } /* float max3(float a, float b, float c) */

46 140 C++ Programming for Non-C Programmers Notes

47 Chapter 6 Functions 141 Functions in Multiple Source Files Functions can reside in separate source files. They are compiled separately then linked together to form the executable program: On Unix: CC main.cpp func1.cpp func2.cpp -o progname In an IDE: Add main.cpp, func1.cpp and func2.cpp to your project. Each file is compiled separately and automatically linked together to create the executable.

48 142 C++ Programming for Non-C Programmers Notes

49 Chapter 6 Functions 143 The Concept of Variable Scope Variables are "written to" and "read from". The scope of a variable is all the functions in a program that can access that variable. Variables can be automatic (local), global, static or extern.

50 144 C++ Programming for Non-C Programmers Notes

51 Chapter 6 Functions 145 Automatic Variables Are local to a function (including main()). Are accessible only to the function in which they are defined. Are created "automatically" each time the function is called. Memory locations that store automatic variables are deallocated upon function exit.

52 146 C++ Programming for Non-C Programmers Notes

53 Chapter 6 Functions 147 Global (external) variables Are defined outside of any function. Are available to all functions, even those compiled separately (by using the extern keyword). Provide an alternative to function arguments and return values for communicating between functions. Local variables with same name as global will prevail.

54 148 C++ Programming for Non-C Programmers Notes

55 Chapter 6 Functions 149 Example: Global Variables /* gcount.cpp */ #include <iostream> using namespace std ; void f(void); int count; /* Global variable */ int main(void) { count = 0; f(); /* Once */ f(); /* Twice */ f(); /* Thrice */ cout << "f called " << count << " times" << endl; return 0; } /* int main(void) */ void f(void) { count++; } /* void f(void) */

56 150 C++ Programming for Non-C Programmers Notes

57 Chapter 6 Functions 151 Static Variables Two uses for static (We'll see the second in a minute). Within a function, static variables retain their values "for next call" when a function exits. /* statv.cpp */ #include <iostream> using namespace std ; void statfunc(int); int main(void) { statfunc(10); statfunc(20); return 0; } /* int main(void) */ void statfunc(int i) { static hold = 0; cout << "Previous hold: " << hold << endl; hold = i; cout << "Current hold: " << hold << endl; } /* void statfunc(int i) */

58 152 C++ Programming for Non-C Programmers Notes

59 Chapter 6 Functions 153 External Static Variables External (defined outside any function) static variables are only accessible within that source file. Useful for preventing name conflicts between separately compiled modules. Because... identically named external statics in different files are different, not the same (huh?).

60 154 C++ Programming for Non-C Programmers Notes

61 Chapter 6 Functions 155 Exercises 1. Write a program that reads four numbers from the keyboard and prints out the minimum, maximum, and average of the numbers. Define four separate float variables for the numbers. BE SURE to modularize the program into separate tasks that input the data, perform the calculations, and report the results. Do you think that an array version of this program would be better? 2. Starting with swmenu.cpp (from the previous chapter), create a menu-driven user interface for a program. Loop till the user chooses exit, and call a function for each switched choice. For now, just confirm to the user that the program entered the function. 3. Split the program from Exercise 1 into separately compilable source files, then compile and run the executable. 4. Write a simple program that calls a function which adds two floats and returns the sum.

62 156 C++ Programming for Non-C Programmers Notes

C++ Programming for Non-C Programmers. Supplement

C++ Programming for Non-C Programmers Supplement C++ Programming for Non-C Programmers C++ Programming for Non-C Programmers Published by ITCourseware, 7245 S. Havana St, Suite 100, Centennial, CO 80112