An Introduction to Programming with C++ Fifth Edition

1. An Introduction to Programming with C++Fifth Edition Chapter 4 Chapter 4: Variables, Constants, and Arithmetic Operators

2. More on the Problem-Solving Process An Introduction to Programming with C++, Fifth Edition

3. Variables and Named Constants • Declare a memory location for each input, processing, and output item in IPO chart • A variable is a type of memory location whose contents can change while program is running • Values of named constant items remain the same each time the program is executed An Introduction to Programming with C++, Fifth Edition

4. Variables and Named Constants (continued) • Requires four memory locations: • Two input items • radius • variable • pi • named constant • One processing item • radius squared • variable • One output item • area • variable An Introduction to Programming with C++, Fifth Edition

5. Selecting a Name for a Memory Location • Identifiers should be descriptive and follow some rules: An Introduction to Programming with C++, Fifth Edition

6. Selecting a Name for a Memory Location (continued) • Most programmers: • Use uppercase letters for named constants • Use lowercase letters for variables • Use camel case if a variable’s name contains two or more words An Introduction to Programming with C++, Fifth Edition

7. Selecting a Name for a Memory Location (continued) An Introduction to Programming with C++, Fifth Edition

8. Selecting a Data Type for a Memory Location These data types, except string, are fundamental data types An Introduction to Programming with C++, Fifth Edition

9. Selecting a Data Type for a Memory Location (continued) • string is a class • Program must include: • #include <string> • using std::string; • C++ contains one or more data types for storing • Integers (whole numbers) • Floating-point numbers (with a decimal place) • Characters (letters, symbols, and numbers that will not be used in calculations) • Boolean values (true and false) An Introduction to Programming with C++, Fifth Edition

10. Selecting a Data Type for a Memory Location (continued) • The data type to use for a memory location depends on the values it will store An Introduction to Programming with C++, Fifth Edition

11. How Data is Stored in Internal Memory An Introduction to Programming with C++, Fifth Edition

12. How Data is Stored in Internal Memory (continued) An Introduction to Programming with C++, Fifth Edition

13. Selecting an Initial Value for a Memory Location • To initialize is to assign an initial value to a memory location • Typically a literal constant • Type can be: numeric, character, or string • A location with bool data type can be initialized with keywords true or false • Typical initialization values • 0 • 0.0 • ‘ ‘ • “” • true, false An Introduction to Programming with C++, Fifth Edition

14. Selecting an Initial Value for a Memory Location (continued) An Introduction to Programming with C++, Fifth Edition

15. Type Conversions • Implicit type conversions can occur when assigning a value to a memory location • Or, when processing calculation statements • Value can be promoted or demoted • Implicit demotion can adversely affect output • Use explicit type conversion (type casting) to convert an item from one data type to another • static_cast operator An Introduction to Programming with C++, Fifth Edition

16. Type Conversions (continued) An Introduction to Programming with C++, Fifth Edition

17. Type Conversions (continued) An Introduction to Programming with C++, Fifth Edition

18. Variables and Named Constants (continued) An Introduction to Programming with C++, Fifth Edition

19. Declaring a Named Constant An Introduction to Programming with C++, Fifth Edition

20. Declaring a Variable An Introduction to Programming with C++, Fifth Edition

21. Declaring a Variable (continued) An Introduction to Programming with C++, Fifth Edition

22. Using an Assignment Statement to Store Data in a Variable An Introduction to Programming with C++, Fifth Edition

23. Using an Assignment Statement to Store Data in a Variable (continued) An Introduction to Programming with C++, Fifth Edition

24. Arithmetic Operators • Precedence numbers indicate order in which computer performs the operation in an expression • Use parentheses to override order of precedence An Introduction to Programming with C++, Fifth Edition

25. Arithmetic Operators (continued) An Introduction to Programming with C++, Fifth Edition

26. Arithmetic Operators (continued) An Introduction to Programming with C++, Fifth Edition

27. Arithmetic Assignment Operators An Introduction to Programming with C++, Fifth Edition

28. Getting Data from the Keyboard • Use >> to get numeric, character, or string values from the keyboard and store them in a variable • Stops reading characters when it encounters a white-space character in the input • Blank, tab, or newline • An alternative is to use getline() An Introduction to Programming with C++, Fifth Edition

29. The getline() Function • When getline() encounters the delimiter character in the input, it consumes the character newline character Items between parentheses in a function’s syntax are the arguments An Introduction to Programming with C++, Fifth Edition

30. The ignore() Function • ignore()instructs computer to read and consume characters entered at keyboard An Introduction to Programming with C++, Fifth Edition

31. The ignore() Function (continued) An Introduction to Programming with C++, Fifth Edition

32. Formatting Floating-Point Numbers • Use fixed stream manipulator to display a floating-point number in fixed-point notation #include <iostream> using std::fixed; • Use scientific stream manipulator for e notation #include <iostream> using std::scientific; • Setprecision stream manipulator controls number of decimal places displayed #include <iomanip> using std::setprecision; An Introduction to Programming with C++, Fifth Edition

33. Formatting Floating-Point Numbers (continued) An Introduction to Programming with C++, Fifth Edition

34. Formatting Floating-Point Numbers (continued) An Introduction to Programming with C++, Fifth Edition

35. Summary • Programs have variables, constants (named, literal), and arithmetic operators (to perform calculations) const dataType constantName = value; dataType variableName [= initialValue]; • Use assignment statement to store data in a variable variableName = expression; • When assigning a value to a memory location, the value should fit the memory location’s data type • Use static_cast operator to convert an item of data from one data type to another An Introduction to Programming with C++, Fifth Edition

36. Summary (continued) • Arithmetic operators have a precedence number • Use parentheses to override order of precedence • Arithmetic assignment operators abbreviate an assignment statement varName arithmeticAssignmentOp expr; • getline() gets a string of characters • ignore() reads and consumes characters entered at the keyboard • fixed and scientific stream manipulators format the display of floating-point numbers An Introduction to Programming with C++, Fifth Edition

37. Application Lesson: Using Variables, Constants, and Arithmetic Operators in a C++ Program • Lab 4.1: Stop and Analyze • Study the program shown in Figure 4-26, then answer the questions • Lab 4.2: • Test program in Figure 4-27 • Lab 4.3: • Modify program so that it allows user to enter the semester hour fee • Lab 4.4: Desk-Check Lab • Lab 4.5: Debugging Lab An Introduction to Programming with C++, Fifth Edition