B VB .NET AND C# QUICK REFERENCE in Font

Make PDF-417 2d barcode in Font B VB .NET AND C# QUICK REFERENCE

static { //p1 //so p1 = }

void MethodC(ref int p1) is a reference to the same memory location as x chages to p1 affect x 10;

Even though they are officially reference types, string parameters act like value type parameters. In other words, you can control their behavior using the ByVal, ByRef, and ref keywords: VB .NET Sub Main() Dim x As String = "A" Dim y As String = "B" MethodA(x, y) Console.WriteLine(x) 'Now shows A-1 Console.WriteLine(y) 'Still shows B End Sub Sub MethodA(ByRef p1 As String, ByVal p2 As String) p1 = "A-1" p2 = "B-1" End Sub C# static void Main() { string x = "A"; string y = "B"; //Pass argument x to parameters p1 MethodC(ref x, y); Console.WriteLine(x);//Now shows A-1 Console.WriteLine(y);//Still shows B } static void MethodC(ref string p1, string p2 ) { p1 = "A-1"; p2 = "B-1"; }

If you are coding in VB .NET, you can use optional parameters. These are just like the standard parameters, but they include a default value. If you do not pass in an argument to the parameter, then the default value will be used. Optional parameters must be listed after any parameter without a default value: VB .NET Sub Main() MethodA("Bob Jones")'Shows Hello Bob Smith MethodA("Bob Jones", "Mr.")'Shows Hello Mr. Bob Smith End Sub Sub MethodA(ByVal name As String, Optional ByVal prefix As String = "") Console.WriteLine("Hello, " & prefix & " " & name) End Sub

Optional parameters are an older way of making methods perform in multiple ways. Both C# and VB .NET can use a new way, which is just to create two methods with the same name but different parameters. When the method is called, .NET will automatically use the number and data types of the arguments to determine which version of the method to call: VB .NET Sub Main() MethodA("Bob Jones")'Shows Hello Bob Smith MethodA("Bob Jones", "Mr.")'Shows Hello Mr. Bob Smith End Sub Sub MethodA(ByVal name As String) Console.WriteLine("Hello, " & " " & name) End Sub Sub MethodA(ByVal name As String, ByVal prefix As String) Console.WriteLine("Hello, " & prefix & " " & name) End Sub C# static void Main() { MethodA("Bob Jones");//Shows Hello Bob Smith MethodA("Bob Jones", "Mr.");//Shows Hello Mr. Bob Smith }

static void MethodA(string name) { Console.WriteLine("Hello, " + " " + name); } static void MethodA(string name, string prefix) { Console.WriteLine("Hello, " + prefix + " " + name); }

Properties are a special type of method. They are used to access and modify variables in a structure or class. Instead of passing arguments to a property, you use the assignment operator, as in MyProperty = 5. With property procedures, you can add code to control the way your program sets a variable s value. This code can also control the way a program gets a variable s values. While we cover property procedures in 6, here is a quick look at what one of these looks like: VB .NET 'This variable is private and must be accessed or 'modified with the property Quantity Private intQuantity As Integer Public Property Quantity () As Integer 'This part of the property procedure runs when code asks to read Quantity Get Return intQuantity End Get 'This part of the property procedure run when code asks to change Quantity Set (ByVal Value As Integer) If Value < 0 Then ' This is an example of some validation code. intQuantity = 0 'Sets the all negative numbers to zero Else intQuantity = Value End If End Set End Property Sub Main() Quantity = 5 'Sets the value of Quantity Console.WriteLine(Quantity) 'Reads the value of Quantity Quantity = -5 'Try to set the value of Quantity to a negitive number Console.WriteLine(Quantity) 'Reads Quantity and shows 0 End Sub