Visual Programming Lecture 4 Operator Precedence Methods Classes

Visual Programming Lecture 4

Operator Precedence

Methods, Classes, Objects, Method Calls, Attributes, Properties Ø Discuss the definitions of Methods, Classes, Objects, Method Calls, Attributes, Properties (Get Accessor and Set Accessor) Ø Create Grade. Book class with the following code and test it: Using system; Public class Grade. Book { public void Display. Message() { Console. Write. Line(“Welcome to the Grade Book!”); } }

Declaring a Method with Parameter Using system; Public class Grade. Book { public void Display. Message(string course. Name) { Course. Write. Line(“Welcome to the grade book for n{0}!”, course. Name); } }

Testing Grade. Book my. Grade. Book = new Grade. Book(); Console. Write. Line(“Please enter the course name: “); String name. Of. Course = Console. Read. Line(); Console. Write. Line(); my. Grade. Book. Display. Message(name. Of. Course);

Instance Variables and Properties Ø Variables declared inside a method are called “local variables” Ø Variables declared inside class but outside method body are called “instance variables” Ø Each object of a class has its own instance of “instance variable” Ø Modify the Grade. Book class as shown on next slide Ø Also discuss UML class diagram

UML Diagram

Public class Grade. Book { Private string course. Name; Public string Course. Name { get { return course. Name; } set { course. Name = value; } Public void Display. Message() { console. Write. Line(“Welcome to the grade book for n{0}!”, Course. Name); } } }

Testing Grade. Book my. Grade. Book = new Grade. Book(); Console. Write. Line(“Initial course name is : ‘{0}’n”, my. Grade. Book. Course. Name); Console. Write. Line(“Please enter the course name: “); my. Grade. Book. Course. Name = Console. Read. Line(); Console. Write. Line(); my. Grade. Book. Display. Message();

Auto Implemented Properties and Constructors Public class Grade. Book { public string Course. Name { get; set; } public Grade. Book (string name) { Course. Name = name; } public void Display. Message() { Console. Write. Line(“Welcome to the grade book for n{0}!”, Course. Name); } }

Testing Grade. Book { Grade. Book grade. Book 1 = new Grade. Book(“C# Programming”); Grade. Book grade. Book 2 = new Grade. Book(“Data Structure”); Console. Write. Line(“grade. Book 1 course name is : {0}”, grade. Book 1. Course. Name); Console. Write. Line(“grade. Book 2 course name is : {0}”, grade. Book 2. Course. Name); }