Chapter 2 Introduction to C++

1. Chapter 2 Introduction to C++ Department of Computer Science Missouri State University

2. Outline • The structure of C++ programs • Cout Objects • The #include directive • Variables and constants • Data Types • Operations • Comments • Programming Style

3. An example // This program calculates a pay check. #include<iostream> using namespace std; void main( ) { int workerPayRate; float workHours, pay; workerPayRate=12; workHours=10.5; pay=workHours workerPayRate; cout<<“A worker earns $”<<pay<<endl; }

4. Comments • Used to document parts of the program • Intended for persons reading the source code of the program: • Indicate the purpose of the program • Describe the use of variables • Explain complex sections of code • Are ignored by the compiler

5. Comments My: // all students grades statistics void main( ) { } David: // sophomore grades statistics void main( ) { } Kevins: // junior grades statistics void main( ) { } Linda: // freshman grades statistics void main( ) { }

6. C++ Style Comments Begin with // through to the end of line: int length = 12; // length in inches int width = 15; // width in inches int area; // calculated area // calculate rectangle area area = length * width;

7. C-Style Comments • Begin with /*, end with */ • Can span multiple lines: /* this is a multi-line C-style comment */ • Can be used like C++ style comments: int area; /* calculated area */

8. An example // This program calculates a pay check. #include<iostream> using namespace std; void main( ) { int workerPayRate; float workHours, pay; workerPayRate=12; workHours=10.5; pay=workHours workerPayRate; cout<<“A worker earns $”<<pay<<endl; }

9. Preprocessor Directive Part • # include <aFileName>

10. An example // This program calculates a pay check. #include<iostream> using namespace std; void main( ) { int workerPayRate; float workHours, pay; workerPayRate=12; workHours=10.5; pay=workHours workerPayRate; cout<<“A worker earns $”<<pay<<endl; }

11. Cheek Glass      Temple ostream cout … …  Namespaces Missouri State Campus C++

12. An example // This program calculates a pay check. #include<iostream> using namespace std; void main( ) { int workerPayRate; float workHours, pay; workerPayRate=12; workHours=10.5; pay=workHours workerPayRate; cout<<“A worker earns $”<<pay<<endl; }

13. Procedure Part • General form of a procedure or a function Return _Type functioName ( parameter list) { Function_body }

14. An example // This program calculates a pay check. #include<iostream> using namespace std; void main( ) { int workerPayRate; float workHours, pay; workerPayRate=12; workHours=10.5; pay=workHours workerPayRate; cout<<“A worker earns $”<<pay<<endl; }

15. Operations : Assignment float currentTemperature; double pi; int Price; currentTemperature = pi = Price = Output cout<<“Current temperature is “ <<currentTemperature<<endl; cout<<“pi=”<<pi<<endl;

16. Arithmetic Operators • Used for performing numeric calculations • C++ has unary, binary, and ternary operators: • unary (1 operand) -5 • binary (2 operands) 13 - 7 • ternary (3 operands) exp1 ? exp2 : exp3

17. Arithmetic Operators • Ternary operator: conditional operator X<0 ? Y=10 : z=20;

18. Binary Arithmetic Operators

19. / Operator • / (division) operator performs integer division if both operands are integers cout << 13 / 5; // displays 2 cout << 91 / 7; // displays 13 • If either operand is floating point, the result is floating point cout << 13 / 5.0; // displays 2.6 cout << 91.0 / 7; // displays 13.0

20. % Operator • % (modulus) operator computes the remainder resulting from integer division cout << 13 % 5; // displays 3 • % requires integers for both operands cout << 13 % 5.0; // error

21. An example // This program calculates a pay check. #include<iostream> using namespace std; void main( ) { int workerPayRate; float workHours, pay; workerPayRate=12; workHours=10.5; pay=workHours workerPayRate; cout<<“A worker earns $”<<pay<<endl; }

22. Cout Object Exercise: 1) cout<<“You got 98 points. Cheers!”; 2) cout<<“You got ”; cout<<“98”; cout<<“ points. ”; cout<<“Cheers!”; 3) cout<<“You got ”<<“98” <<“ ponts. ”<<“Cheers!”; 4) cout<<“You got ”<<98<<“ points. Cheers!”; 5) cout<<“You got ”<<98<<“ points.”<<endl; cout<<“Cheers!”;

23. Common escape sequences • Exercise 1 He says “I’m genius!” • Exercise 2 My hw is in the directory \upload\csc125\hl

24. Programming Style • The visual organization of the source code • Includes the use of spaces, tabs, and blank lines • Does not affect the syntax of the program • Affects the readability of the source code

25. Programming Style // This program calculates a pay check. #include<iostream> using namespace std; void main ( ){ int workerPayRate; float workHours, pay;workerPayRate=12;workHours=10.5; pay=workHours workerPayRate; cout<< “A worker earns $”<<pay<<endl; }

26. Programming Style void main( ) { float height=4, width=3.5, radius=12.1, base=9, top=5.2; float area1, area2, area3, area4; area1=height width; area2=3.14 radius radius; area3=height base/2; area4=(top+base) width/2; cout<<“Areas:”<<area1<<“, ”<<area2<<“, ” <<area3<<“, ”<<area4<<endl; }

27. Programming Style Common elements to improve readability: • Braces { } aligned vertically • Indentation of statements within a set of braces • Blank lines between declaration and other statements • Long statements wrapped over multiple lines with aligned operators

28. Standard and Prestandard C++ Older-style C++ programs: • Use .h at end of header files: #include <iostream.h> • Do not use using namespace convention • May not compile with a standard C++ compiler