1. Starting Out with C++, 3 rd Edition 1 Chapter 2. Introduction to C++

2. Starting Out with C++, 3 rd Edition 2 2.1 The Parts of a C++ Program C++ programs have parts and components that serve specific purposes.

3. Starting Out with C++, 3 rd Edition 3 Program 2-1 //A simple C++ program #include void main (void) { cout<< “Programming is great fun!”; } Program Output: Programming is great fun!

4. Starting Out with C++, 3 rd Edition 4 Table 2-1

5. Starting Out with C++, 3 rd Edition 5 2.2The cout Object Use the cout object to display information on the computer’s screen. The cout object is referred to as the standard output object. l Its job is to output information using the standard output device

6. Starting Out with C++, 3 rd Edition 6 Program 2-2 // A simple C++ program #include void main (void) { cout<< “Programming is “ << “great fun!”; } Output: Programming is great fun!

7. Starting Out with C++, 3 rd Edition 7 Program 2-3 // A simple C++ program #include void main (void) { cout<< “Programming is “; cout << “ great fun!”; } Output: Programming is great fun!

8. Starting Out with C++, 3 rd Edition 8 Program 2-4 // An unruly printing program #include void main(void) { cout << "The following items were top sellers"; cout << "during the month of June:"; cout << "Computer games"; cout << "Coffee"; cout << "Aspirin"; } Program Output The following items were top sellersduring the month of June:Computer gamesCoffeeAspirin

9. Starting Out with C++, 3 rd Edition 9 New lines cout does not produce a newline at the end of a statement To produce a newline, use either the stream manipulator endl or the escape sequence \n

10. Starting Out with C++, 3 rd Edition 10 Program 2-5 // A well-adjusted printing program #include void main(void) { cout << "The following items were top sellers" << endl; cout << "during the month of June:" << endl; cout << "Computer games" << endl; cout << "Coffee" << endl; cout << "Aspirin" << endl; }

11. Starting Out with C++, 3 rd Edition 11 Program Output The following items were top sellers during the month of June: Computer games Coffee Aspirin

12. Starting Out with C++, 3 rd Edition 12 Program 2-6 // Another well-adjusted printing program #include void main(void) { cout << "The following items were top sellers" << endl; cout << "during the month of June:" << endl; cout << "Computer games" << endl << "Coffee"; cout << endl << "Aspirin" << endl; }

13. Starting Out with C++, 3 rd Edition 13 Program Output The following items were top sellers during the month of June: Computer games Coffee Aspirin

14. Starting Out with C++, 3 rd Edition 14 Program 2-7 // Yet another well-adjusted printing program #include using namespace std; void main(void) { cout << "The following items were top sellers\n"; cout << "during the month of June:\n"; cout << "Computer games\nCoffee"; cout << "\nAspirin\n"; }

15. Starting Out with C++, 3 rd Edition 15 Program Output The following items were top sellers during the month of June: Computer games Coffee Aspirin

16. Starting Out with C++, 3 rd Edition 16 Table 2-2

17. Starting Out with C++, 3 rd Edition 17 2.3 The #include Directive The #include directive causes the contents of another file to be inserted into the program Preprocessor directives are not C++ statements and do not require semicolons at the end

18. Starting Out with C++, 3 rd Edition 18 2.5 Variables and Constants Variables represent storage locations in the computer’s memory. Constants are data items whose values do not change while the program is running. Every variable must have a declaration.

19. Starting Out with C++, 3 rd Edition 19 Program 2-8 #include void main(void) { int value; value = 5; cout << “The value is “ << value << endl; } Program Output: The value is 5

20. Starting Out with C++, 3 rd Edition 20 Assignment statements: Value = 5; //This line is an assignment statement. The assignment statement evaluates the expression on the right of the equal sign then stores it into the variable named on the left of the equal sign The data type of the variable was in integer, so the data type of the expression on the right should evaluate to an integer as well.

21. Starting Out with C++, 3 rd Edition 21 Constants A variable is called a “variable” because its value may be changed. A constant, on the other hand, is a data item whose value does not change during the program’s execution.

22. Starting Out with C++, 3 rd Edition 22 Program 2-10 #include void main (void) { int apples; apples = 20; cout<< “Today we sold “ << apples << “ bushels\n”; cout << “of apples.\n”; }

23. Starting Out with C++, 3 rd Edition 23 Program Output Today we sold 20 bushels of apples. Where are the constants in program 2-10?

24. Starting Out with C++, 3 rd Edition 24 Constants from Program 2-10

25. Starting Out with C++, 3 rd Edition 25 2.6 Focus on Software Engineering: Identifiers Must not be a key word Should be mnemonic (give an indication of what the variable is used for) The first character must be a letter or an underscore The remaining may be letters, digits, or underscores Upper and lower case letters are distinct

26. Starting Out with C++, 3 rd Edition 26 Table 2-3 The C++ Key Words

27. Starting Out with C++, 3 rd Edition 27 Table 2-4 Some Variable Names Variable NameLegal or Illegal? dayOfWeek Legal 3dGraph Illegal. Cannot begin with a digit. _employee_num Legal june1997 Legal Mixture#3 Illegal. Cannot use # symbol.

28. Starting Out with C++, 3 rd Edition 28 2.7Integer Data Types There are many different types of data. Variables are classified according to their data type, which determines the kind of information that may be stored in them. Integer variables only hold whole numbers.

29. Starting Out with C++, 3 rd Edition 29 Table 2-5

30. Starting Out with C++, 3 rd Edition 30 Program 2-11 // This program has variables of several of the integer types. #include void main(void) { int checking; unsigned int miles; long days; checking = -20; miles = 4276; days = 184086; cout << "We have made a long journey of " << miles; cout << " miles.\n"; cout << "Our checking account balance is " << checking; cout << "\nExactly " << days << " days ago Columbus "; cout << "stood on this spot.\n"; }

31. Starting Out with C++, 3 rd Edition 31 Program Output We have made a long journey of 4276 miles. Our checking account balance is -20 Exactly 184086 days ago Columbus stood on this spot.

32. Starting Out with C++, 3 rd Edition 32 Program 2-12 // This program shows three variables declared on the same // line. #include void main(void) { int floors,rooms,suites; floors = 15; rooms = 300; suites = 30; cout << "The Grande Hotel has " << floors << " floors\n"; cout << "with " << rooms << " rooms and " << suites; cout << " suites.\n"; }

33. Starting Out with C++, 3 rd Edition 33 Program Output The Grande Hotel has 15 floors with 300 rooms and 30 suites.

34. Starting Out with C++, 3 rd Edition 34 Hexadecimal and Octal Constants Hexadecimal numbers are preceded by 0x l Hexadecimal F4 would be expressed in C++ as 0xF4 Octal numbers are preceded by a 0 l Octal 31 would be written as 031

35. Starting Out with C++, 3 rd Edition 35 2.8 The char Data Type Usually 1 byte long Internally stored as an integer ASCII character set shows integer representation for each character ‘A’ == 65, ‘B’ == 66, ‘C’ == 67, etc. Single quotes denote a character, double quotes denote a string

36. Starting Out with C++, 3 rd Edition 36 Program 2-13 // This program demonstrates the close relationship between // characters and integers. #include void main(void) { char letter; letter = 65; cout << letter << endl; letter = 66; cout << letter << endl; }

37. Starting Out with C++, 3 rd Edition 37 Program Output ABAB

38. Starting Out with C++, 3 rd Edition 38 Program 2-14 // This program uses character constants #include void main(void) { char letter; letter = 'A'; cout << letter << endl; letter = 'B'; cout << letter << endl; }

39. Starting Out with C++, 3 rd Edition 39 Program Output ABAB

40. Starting Out with C++, 3 rd Edition 40 C-Strings C-Strings are consecutive sequences of characters and can occupy several bytes of memory. C-Strings always have a null terminator at the end. This marks the end of the string. Escape sequences are always stored internally as a single character.

41. Starting Out with C++, 3 rd Edition 41 Program 2-15 // This program uses character constants #include void main(void) { char letter; letter = 'A'; cout << letter << '\n'; letter = 'B'; cout << letter << '\n'; }

42. Starting Out with C++, 3 rd Edition 42 Program Output ABAB

43. Starting Out with C++, 3 rd Edition 43 Review key points regarding characters, strings, and C-strings: Printable characters are internally represented by numeric codes. Most computers use ASCII codes for this purpose. Characters occupy a single byte of memory. C-Strings are consecutive sequences of characters and can occupy several bytes of memory. C-Strings always have a null terminator at the end. This marks the end of the C-string. Character constants are always enclosed in single quotation marks. String constants are always enclosed in double quotation marks. Escape sequences are always stored internally as a single character.

44. Starting Out with C++, 3 rd Edition 44 2.9The C++ string Class The string class is an abstract data type. It provides capabilities that make working with strings easy and intuitive. You must us the #include statement.

45. Starting Out with C++, 3 rd Edition 45 2.10 Floating Point Data Types Floating point data types are used to declare variables that can hold real numbers

46. Starting Out with C++, 3 rd Edition 46 Table 2-7

47. Starting Out with C++, 3 rd Edition 47 Program 2-17 // This program uses floating point data types #include void main(void) { float distance; double mass; distance = 1.495979E11; mass = 1.989E30; cout << "The Sun is " << distance << " kilometers away.\n"; cout << "The Sun\'s mass is " << mass << " kilograms.\n"; }

48. Starting Out with C++, 3 rd Edition 48 Program Output The Sun is 1.4959e+11 kilometers away. The Sun's mass is 1.989e+30 kilograms.

49. Starting Out with C++, 3 rd Edition 49 Floating Point Constants May be expressed in a variety of ways E notation decimal notation (no commas)

50. Starting Out with C++, 3 rd Edition 50 2.11 The bool Data Type Boolean variables are set to either true or false

51. Starting Out with C++, 3 rd Edition 51 Program 2-18 #include void main (void) { bool boolValue; boolValue = true; cout << boolValue << endl; boolValue = false; cout << boolValue << endl; }

52. Starting Out with C++, 3 rd Edition 52 Program Output 1 0 Internally, true is represented as the number 1 and false is represented by the number 0.

53. Starting Out with C++, 3 rd Edition 53 2.12 Focus on Software Engineering: Determining the Size of a Data Type The sizeof operator may be used to determine the size of a data type on any system. cout << “The size of an integer is “ << sizeof(int);

54. Starting Out with C++, 3 rd Edition 54 Program 2-19 #include void main (void) { long double apple; cout << “The size of an integer is “ << sizeof(int); cout << “ bytes.\n”; cout << “The size of a long integer is “ << sizeof(long); cout << “ bytes.\n”; cout << “An apple can be eaten in “ << sizeof(apple); cout << “ bytes!\n”; }

55. Starting Out with C++, 3 rd Edition 55 Program Output The size of an integer is 4 bytes. The size of a long integer is 4 bytes. An apple can be eaten in 8 bytes!

56. Starting Out with C++, 3 rd Edition 56 2.13 Focus on Software Engineering: Variable Assignment and Initialization An assignment operation assigns, or copies, a value into a variable. When a value is assigned to a variable as part of the variable’s declaration, it is called an initialization.

57. Starting Out with C++, 3 rd Edition 57 Program 2-20 #include void main (void) { int month = 2, days = 28; cout << “Month “ << month << “ has “ << days << “ days.\n”; } Program output: Month 2 has 28 days.

58. Starting Out with C++, 3 rd Edition 58 2.14 Focus on Software Engineering: Scope A variable’s scope is the part of the program that has access to the variable. A variable must be declared before it is used.

59. Starting Out with C++, 3 rd Edition 59 Program 2-21 // This program can't find its variable #include void main(void) { cout << Value; int Value = 100; }

60. Starting Out with C++, 3 rd Edition 60 2.15 Arithmetic Operators There are many operators for manipulating numeric values and performing arithmetic operations. Generally, there are 3 types of operators: unary, binary, and ternary. l Unary operators operate on one operand l Binary operators require two operands l Ternary operators need three operands

61. Starting Out with C++, 3 rd Edition 61 Table 2-8

62. Starting Out with C++, 3 rd Edition 62 Program 2-22 // This program calculates hourly wages // The variables in function main are used as follows: // regWages: holds the calculated regular wages. // basePay: holds the base pay rate. // regHours: holds the number of hours worked less overtime. //otWages: holds the calculated overtime wages. // otPay: holds the payrate for overtime hours. // otHours: holds the number of overtime hours worked. //totalWages: holds the total wages. #include void main(void) { float regWages, basePay = 18.25, regHours = 40.0; float otWages, otPay = 27.78, otHours = 10; float totalWages; regWages = basePay * regHours; otWages = otPay * otHours; totalWages = regWages + otWages; cout << "Wages for this week are $" << totalWages << endl; }

63. Starting Out with C++, 3 rd Edition 63 2.16Comments Comments are notes of explanation that document lines or sections of a program. Comments are part of a program, but the compiler ignores them. They are intended for people who may be reading the source code. Commenting the C++ Way // Commenting the C Way /* */

64. Starting Out with C++, 3 rd Edition 64 Program 2-23 // PROGRAM: PAYROLL.CPP // Written by Herbert Dorfmann // This program calculates company payroll // Last modification: 3/30/96 #include void main(void) { float payRate;// holds the hourly pay rate float hours;// holds the hours worked int empNum;// holds the employee number (The remainder of this program is left out.)

65. Starting Out with C++, 3 rd Edition 65 Program 2-24 // PROGRAM: PAYROLL.CPP // Written by Herbert Dorfmann // Also known as "The Dorfmiester" // Last modification: 3/30/96 // This program calculates company payroll. // Payroll should be done every Friday no later than // 12:00 pm. To start the program type PAYROLL and // press the enter key. #include // Need the iostream file because // the program uses cout. void main(void) // This is the start of function main. {// This is the opening brace for main. float payRate;// payRate is a float variable. // It holds the hourly pay rate. float hours;// hours is a float variable too. // It holds the hours worked. int empNum;// empNum is an integer. // It holds the employee number. (The remainder of this program is left out.)

66. Starting Out with C++, 3 rd Edition 66 Program 2-25 /* PROGRAM: PAYROLL.CPP Written by Herbert Dorfmann This program calculates company payroll Last modification: 3/30/96 */ #include void main(void) { float payRate;/* payRate holds hourly pay rate */ float hours;/* hours holds hours worked */ int empNum;/* empNum holds employee number */ (The remainder of this program is left out.)

67. Starting Out with C++, 3 rd Edition 67 Program 2-26 /* PROGRAM: PAYROLL.CPP Written by Herbert Dorfmann This program calculates company payroll Last modification: 3/30/96 */ #include void main(void) { float payRate;// payRate holds the hourly pay rate float hours;// hours holds the hours worked int empNum;// empNum holds the employee number (The remainder of this program is left out.)

68. Starting Out with C++, 3 rd Edition 68 2.17Focus on Software Engineering: Programming Style Program style refers to the way a programmer uses identifiers, spaces, tabs, blank lines, and punctuation characters to visually arrange a program’s source code. l Generally, C++ ignores white space. l Indent inside a set of braces. l Include a blank line after variable declarations.

69. Starting Out with C++, 3 rd Edition 69 Program 2-27 #include void main(void){float shares=220.0;float avgPrice=14.67;cout <<"There were "<<shares<<" shares sold at $"<<avgPrice<<" per share.\n";} Program Output There were 220 shares sold at $14.67 per share.

70. Starting Out with C++, 3 rd Edition 70 Program 2-28 // This example is much more readable than Program 2-26. #include void main(void) { float shares = 220.0; float avgPrice = 14.67; cout << "There were " << shares << " shares sold at $"; cout << avgPrice << " per share.\n"; } Program Output There were 220.0 shares sold at $14.67 per share.