Slide 1Slide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18COSC 181 – Foundations of Computer ProgrammingClass 5ATM Requirements Spec.Introduce you to O.O. programming with this exampleThreaded through the next several chaptersFirst Step - Gather RequirementsATM – allow users to perform basic bankingOne account per userUsers should be able toView balanceWithdraw cashDeposit fundsHardwareScreen/Keypad/Cash Dispenser/Deposit SlotKey Elements - Things learn from talking to the bank managersATM begins each day stocked with 500 $20 bills.Each user is asked to type in his own account id.All output from ATM occurs on screen.Bank wants you to write the softwareneed not worry about hardware interfacesoftware first runs on your computermonitor simulates the ATM screenkeyboard simulates ATM keypadWhat are some activities performed at an ATM?User Experience ModelA.K.A - Use CasesStandard UML (Unified Modeling Language) Diagram. We’ll talk about other UML diagrams at the end of today’s slides.The User Experience1. Screen displays a welcome message and prompts for the account number2. User enters 5 digit account number3. ATM asks user to enter PIN4. User enters 5 digit PIN, using the keypad5. ATM checks Acct#/PIN comboif valid : ATM displays main menuif invalid: ATM displays an appropriate messageWhat are the items that should be on the main menu?Main MenuMain Menu: 1 - View my balance 2 - Withdraw cash 3 - Deposit funds 4 - ExitEnter a choice1 - View My BalanceATM displays a screen with the user’s balance2 - Withdraw Cash (Menu)Withdrawal options:1 - $20 4 - $1002 - $40 5 - $2003 - $60 6 - Cancel transactionChoose a withdrawal option (1-6):System States1. Withdrawal amount greater than balanceerror message : return to previous menu2. Withdrawal amount less than balance(2 cases)if enough money in dispenserdebit account and dispense moneydisplay message reminding user to take moneyif not enough money in dispenserdisplay error and return to previous menu3 - Deposit FundsEnter a deposit amount (0 to cancel): (Again – 2 Cases to Consider)3. Deposit amount enteredATM prompts user to insert envelopeonce envelope inserted ATM credits balance4. 0 enteredATM returns to previous menuDesigning the System1. Use Case Diagramsmodels how the various users will use the system2. Class Diagrams (Chapter 3)classes define objectseach noun described in requirements could be a class3. State Machine Diagrams (Chapter 3)state - value of all object attributesmodels how the classes will interactContinued1. Activity Diagrams (Chapter 5)models an objects workflow2. Communication Diagrams (Chapter 7)models interaction amongst objects3. Sequence Diagrams (Chapter 7)models when interactions occur between objectsGradeBook ClassReferencing Fig 3.1Defining a classTelling the compiler what member functions and data members belong to the classMember FunctiondisplayMessage()Displays a message on the screenDefining the GradeBook ClassLine 9 – 17//GradeBook class definitionclass GradeBook{public://function that displays a messagevoid displayMessage(){cout << “Welcome to the Grade Book!” << endl;}};Classes have identifiers, just like variables  Follow same rulesBy convention, class identifiers begin with a capital letter.Uses “camel case” notation  FirstSecondEasier to readEvery class is enclosed in { }, with a ; after the closing bracketpublic: indicates that the affected part of the class (members and functions) are accessible by functions outside the class (i.e. – main())Functionsvoid displayMessage() is a functionmain() is also a functionUnlike main(), displayMessage() is not called automaticallyFunctions perform tasks and might return valuesWhat about displayMessage() ?Functions (con’t) void displayMessage()void – return type displayMessage – function name (identifier)By convention, first letter lower-case() – indicates that this is a functionEmpty parenthesis indicate that no additional data is needed for the function to perform its task{ } – all statements in a function appear between braces (no semicolon)Using the GradeBook class in a programWant to “call” displayMessage() to display the message on the screenCan’t call a member function until you create an instance of the classLines 22 and 23 in Fig 3.1GradeBook myGradeBook;“GradeBook” type is defined because we included the GradeBook class in the codemyGradeBook.displayMessage();“dot operator”UML: Class DiagramsClasses represented as a rectangle with 3 compartmentsClasses NameClasses Attributes C++ Data Members (more on this later)Classes