.NODE

G.3. Class Screen

Class Screen (Figs. G.3G.4) represents the screen of the ATM and encapsulates all aspects of displaying output to the user. Class Screen approximates a real ATM's screen with a computer monitor and outputs text messages using cout and the stream insertion operator (<<). In this case study, we designed class Screen to have one operationdisplayMessage. For greater flexibility in displaying messages to the Screen, we now declare three Screen member functionsdisplayMessage, displayMessageLine and displayDollarAmount. The prototypes for these member functions appear in lines 1214 of Fig. G.3.

Figure G.3. Screen class definition.

 1 // Screen.h
 2 // Screen class definition. Represents the screen of the ATM.
 3 #ifndef SCREEN_H
 4 #define SCREEN_H
 5
 6 #include 
 7 using std::string;
 8
 9 class Screen
10 {
11 public:
12 void displayMessage( string ) const; // output a message
13 void displayMessageLine( string ) const; // output message with newline
14 void displayDollarAmount( double ) const; // output a dollar amount
15 }; // end class Screen
16
17 #endif // SCREEN_H

Figure G.4. Screen class member-function definitions.

(This item is displayed on pages 1293 - 1294 in the print version)

 1 // Screen.cpp
 2 // Member-function definitions for class Screen.
 3 #include 
 4 using std::cout;
 5 using std::endl;
 6 using std::fixed;
 7
 8 #include 
 9 using std::setprecision;
10
11 #include "Screen.h" // Screen class definition
12
13 // output a message without a newline
14 void Screen::displayMessage( string message ) const
15 {
16 cout << message;
17 } // end function displayMessage
18
19 // output a message with a newline
20 void Screen::displayMessageLine( string message ) const
21 {
22 cout << message << endl;
23 } // end function displayMessageLine
24
25 // output a dollar amount
26 void Screen::displayDollarAmount( double amount ) const
27 {
28 cout << fixed << setprecision( 2 ) << "$" << amount;
29 } // end function displayDollarAmount

Screen Class Member-Function Definitions

Figure G.4 contains the member-function definitions for class Screen. Line 11 #includes the Screen class definition. Member function displayMessage (lines 1417) takes a string as an argument and prints it to the console using cout and the stream insertion operator (<<). The cursor stays on the same line, making this member function appropriate for displaying prompts to the user. Member function displayMessageLine (lines 2023) also prints a string, but outputs a newline to move the cursor to the next line. Finally, member function displayDollarAmount (lines 2629) outputs a properly formatted dollar amount (e.g., $123.45). Line 28 uses stream manipulators fixed and setprecision to output a value formatted with two decimal places. See Chapter 15, Stream Input/Output, for more information about formatting output.

Introduction to Computers, the Internet and World Wide Web

Introduction to C++ Programming

Introduction to Classes and Objects

Control Statements: Part 1

Control Statements: Part 2

Functions and an Introduction to Recursion

Arrays and Vectors

Pointers and Pointer-Based Strings

Classes: A Deeper Look, Part 1

Classes: A Deeper Look, Part 2

Operator Overloading; String and Array Objects

Object-Oriented Programming: Inheritance

Object-Oriented Programming: Polymorphism

Templates

Stream Input/Output

Exception Handling

File Processing

Class string and String Stream Processing

Web Programming

Searching and Sorting

Data Structures

Bits, Characters, C-Strings and structs

Standard Template Library (STL)

Other Topics

Appendix A. Operator Precedence and Associativity Chart

Appendix B. ASCII Character Set

Appendix C. Fundamental Types

Appendix D. Number Systems

Appendix E. C Legacy Code Topics

Appendix F. Preprocessor

Appendix G. ATM Case Study Code

Appendix H. UML 2: Additional Diagram Types

Appendix I. C++ Internet and Web Resources

Appendix J. Introduction to XHTML

Appendix K. XHTML Special Characters

Appendix L. Using the Visual Studio .NET Debugger

Appendix M. Using the GNU C++ Debugger

Bibliography

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C++ How to Program
C++ How to Program (5th Edition)
ISBN: 0131857576
EAN: 2147483647
Year: 2004
Pages: 627
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