2. Pemrograman VisualMinggu …6… Page 1 MINGGU Ke Enam Pemrograman Visual Pokok Bahasan: Module, Class & Methods Tujuan Instruksional Khusus: Mahasiswa dapat menjelaskan dan mengaplikasikan konsep Methods pada Visual Basic 2008 Referensi: Deitel Deitel, Visual Basic 2008 (2009), How to Program, Prentice Hall. Chapter 7

3. Pemrograman VisualMinggu …6… Page 2 Agenda Subroutines: Methods that do not return a value Functions : Methods that Return a Value Shared Methods and Class Math Declaring Methods with Multiple parameter Option Strict and Data-Type Conversions Value Types and Reference Types Pass-by-Value VS Pass-by-Reference Scope of Declaration Random number Generation Method Overloading Optional Parameter Recursion

4. Pemrograman VisualMinggu …6… Page 3 Procedure or Subroutines Tidak mengembalikan nilai Bisa memiliki satu atau lebih parameter atau tidak sama sekali Examples: Panjang, Lebar dan Keliling Persegi Panjang

5. Pemrograman VisualMinggu …6… Page 4 Module Module1 Sub Main() hitungKeliling(2, 4) hitungKeliling(6, 5) hitungKeliling(10, 4) hitungKeliling(3, 10) Console.Readkey() End Sub Sub hitungKeliling(ByVal panjang As Integer, ByVal lebar As Integer) Console.WriteLine("Keliling Persegi Panjang adalah {0}", panjang * lebar) End Sub End Module Example Procedure or Subroutines

6. Pemrograman VisualMinggu …6… Page 5 Function Mengembalikan nilai Bisa memiliki satu atau lebih parameter atau tidak sama sekali Examples: Panjang Lebar dan Keliling Persegi Panjang

7. Pemrograman VisualMinggu …6… Page 6 Module Module1 Sub Main() Console.WriteLine("Keliling Persegi Panjang dari 2 dan 4 adalah {0}", hitungKeliling(2, 4)) Console.Readkey() End Sub Function hitungKeliling(ByVal panjang As Integer, ByVal lebar As Integer) As Integer Return 2 * (panjang + lebar) End Function End Module Example Function

8. Pemrograman VisualMinggu …6… Page 7 Share Methods and Class Math Share methods are associated with the class, but not with any specific object of the class; they perform tasks that do not depend on the contents of any object You call a shared method by specifying the name of the class or module in which the method is declare, followed by the dot (.) separator and the method name. Any variable declared with keyword const is constant, its value cannot be changed after the variable is initiated. Constants are implicitly shared

9. Pemrograman VisualMinggu …6… Page 8 Example the Math Class Methods

10. Pemrograman VisualMinggu …6… Page 9 Declaring Methods with Multiple Parameter In a method with more than one parameter, the parameters are specified as a comma-separated list. There must be one argument in the method call for each parameter in the method declaration (except in the case of optional parameters). The type of each argument must be consistent with the type of the corresponding parameter Methods can return at most one value, but the returned value could be a reference to an object that contains many values. Give Example about Declaring Methods with Multiple parameter Figure 07_05 and 07_06

11. Pemrograman VisualMinggu …6… Page 10 Option Strict and Data-Type Conversions Option Explicit forces you to explicitly declare all variables before they are used in a program. Option Strict cause the compiler to check all conversions and requires you to perform an explicit conversion for all narrowing conversions that could cause data loss or program termination.

12. Pemrograman VisualMinggu …6… Page 11 Value Types and Reference Types Both value types and reference types include primitive types and types that you can create. The primitive value type include the integral types (Byte, SByte, Short, UShort, Integer, UInteger, Long and ULong), the floating-point types (Single and Double) and types Boolean, Date, Decimal, and Char. There is only one primitive reference type String. Reference types can be created by defining classes, modules, interface and delegates. Value type can be created by defining a structures and enumerations. Give Example about Value Types and Reference Types Figure 07_11

13. Pemrograman VisualMinggu …6… Page 12 Pass-by-Value VS Pass-by-reference When an argument is passes by value, the program makes a copy of the argument’s value and passes that copy to the called method. With pass-by- value, changes to the called method’s copy do not effect the original variable’s value. When an argument is passed by reference, the caller gives the called method the ability to access and modify the caller’s original data directly.

14. Pemrograman VisualMinggu …6… Page 13 Scope of Declaration The scope of a declaration is the portion of the program that can refer to the declared entity by it’s name, without qualification. If a local variable or parameter in a method has the same name as a field, the member is “hidden” until the block terminates execution--this is called shadowing. Give Example about Scope of Declaration Figure 07_12 – 07_13

15. Pemrograman VisualMinggu …6… Page 14 Random Number Generation

16. Pemrograman VisualMinggu …6… Page 15 Method Overloading Method overloading allows you to create multiple methods with the same name but differing numbers and types of parameters or with different orders of the parameters (by type) Overloaded methods are distinguished by their signatures, which are a combination of the method’s name and parameter types, and the order of the parameter (by type)

17. Pemrograman VisualMinggu …6… Page 16 Example Method Overloading

18. Pemrograman VisualMinggu …6… Page 17 Optional Parameter Methods can have optional parameters. Declaring a parameter as optional allows the calling method to vary the number of arguments to pass. Optional parameters specify a default value that is assigned to the parameter if the optional argument is not passed. For an optional parameter, the caller has the option of passing that particular argument. You can create methods with one or more optional parameters. All optional parameter, however must be placed to the right of the method’s non optional parameters. Default values can be used only with parameters declared as Optional String method IsNullOrEmpty returns True if its argument is the value Nothing or the empty string;otherwise, it returns False

19. Pemrograman VisualMinggu …6… Page 18 Example Optional Parameter

20. Pemrograman VisualMinggu …6… Page 19 Recursion A recursive methods calls itself either directly or indirectly (i.e., through another method) A recursive method knows how to solve only the simplest case(s)—the base case(s). If the method is called with a base case, it returns a result. If the method is called with a more complex problem, it divides the problem into a base case and a recursion step that resembles the original problem but is a slightly simpler or smaller version of it. The recursion step executes while the original call to the method is still “open”. The recursion step can result in many more recursive calls as the method divides each new sub problem into two conceptual pieces

21. Pemrograman VisualMinggu …6… Page 20 Example Recursion

22. Pemrograman VisualMinggu …6… Page 21 Questions & Answers

23. Pemrograman VisualMinggu …6… Page 22 Thank You