1:  Imports System

   2:   

   3:  Namespace Hello

   4:     Class HelloWorld

   5:        Overloads Shared Sub Main(ByVal args() As String)

   6:           Dim name As String = "VB.NET"

   7:   

   8:           'See if an argument was passed from the command line

   9:            If args.Length = 1 Then name = args(0)

  10:   

  11:            Console.WriteLine("Hello, " & name & "!")

  12:        End Sub

  13:     End Class

  14:  End Namespace 

   1:  using System;

   2:   

   3:  namespace Hello {

   4:     public class HelloWorld {

   5:        public static void Main(string[] args) {

   6:           string name = "C#";

   7:   

   8:           // See if an argument was passed from the command line

   9:           if (args.Length == 1)

  10:              name = args[0];

  11:           Console.WriteLine("Hello, " + name + "!");

  12:        }

  13:     }

  14:  } 

   1:  ' Single line only

   2:   

   3:  REM Single line only

   4:   

   5:  ''' <summary>XML comments</summary>

   1:  // Single line

   2:  /* Multiple

   3:      line  */

   4:  /// <summary>XML comments on single line</summary>

   5:  /** <summary>XML comments on multiple lines</summary> */

   1:  'Value Types

   2:  Boolean

   3:  Byte, SByte

   4:  Char

   5:  Short, UShort, Integer, UInteger, Long, ULong

   6:  Single, Double

   7:  Decimal

   8:  Date   (alias of System.DateTime)

   9:  structures

  10:  enumerations

  11:   

  12:  'Reference Types

  13:  objects

  14:  String

  15:  arrays

  16:  delegates

  17:   

  18:  'Initializing

  19:  Dim correct As Boolean = True

  20:  Dim b As Byte = &H2A   'hex or &O52 for octal

  21:  Dim person As Object = Nothing

  22:  Dim name As String = "Dwight"

  23:  Dim grade As Char = "B"c

  24:  Dim today As Date = #12/31/2010 12:15:00 PM#

  25:  Dim amount As Decimal = 35.99@

  26:  Dim gpa As Single = 2.9!

  27:  Dim pi As Double = 3.14159265

  28:  Dim lTotal As Long = 123456L

  29:  Dim sTotal As Short = 123S

  30:  Dim usTotal As UShort = 123US

  31:  Dim uiTotal As UInteger = 123UI

  32:  Dim ulTotal As ULong = 123UL

  33:   

  34:  'Nullable Types

  35:  Dim x? As Integer = Nothing

  36:   

  37:  'Anonymous Types

  38:  Dim stu = New With {.Name = "Sue", .Gpa = 3.4}

  39:  Dim stu2 = New With {Key .Name = "Bob", .Gpa = 2.9}

  40:   

  41:  'Implicitly Typed Local Variables

  42:  Dim s = "Hello!"

  43:  Dim nums = New Integer() {1, 2, 3}

  44:  Dim hero = New SuperHero With {.Name = "Batman"}

  45:   

  46:  'Type Information

  47:  Dim x As Integer

  48:  Console.WriteLine(x.GetType())          ' System.Int32

  49:  Console.WriteLine(GetType(Integer))   ' System.Int32

  50:  Console.WriteLine(TypeName(x))        ' Integer

  51:   

  52:  Dim c as New Circle

  53:  isShape = TypeOf c Is Shape   ' True if c is a Shape

  54:  isSame = o1 Is o2   // True if o1 and o2 reference same object

  55:   

  56:  'Type Conversion / Casting

  57:  Dim d As Single = 3.5

  58:  Dim i As Integer = CType(d, Integer)   ' set to 4 (Banker's rounding)

  59:  i = CInt(d)  ' same result as CType

  60:  i = Int(d)    ' set to 3 (Int function truncates the decimal)

  61:   

  62:  Dim s As New Shape

  63:  Dim c As Circle = TryCast(s, Circle)   ' Returns Nothing if type cast fails

  64:  c = DirectCast(s, Circle)   ' Throws InvalidCastException if type cast fails 

   1:  //Value Types

   2:  bool

   3:  byte, sbyte

   4:  char

   5:  short, ushort, int, uint, long, ulong

   6:  float, double

   7:  decimal

   8:  DateTime   (not a built-in C# type)

   9:  structs

  10:  enumerations

  11:   

  12:  //Reference Types

  13:  objects

  14:  string

  15:  arrays

  16:  delegates

  17:   

  18:  //Initializing

  19:  bool correct = true;

  20:  byte b = 0x2A;   // hex

  21:  object person = null;

  22:  string name = "Dwight";

  23:  char grade = 'B';

  24:  DateTime today = DateTime.Parse("12/31/2010 12:15:00 PM");

  25:  decimal amount = 35.99m;

  26:  float gpa = 2.9f;

  27:  double pi = 3.14159265;   // or 3.14159265D

  28:  long lTotal = 123456L;

  29:  short sTotal = 123;

  30:  ushort usTotal = 123;

  31:  uint uiTotal = 123;   // or 123U

  32:  ulong ulTotal = 123;   // or 123UL

  33:   

  34:  //Nullable Types

  35:  int? x = null;

  36:   

  37:  //Anonymous Types

  38:  var stu = new {Name = "Sue", Gpa = 3.5};

  39:  var stu2 = new {Name = "Bob", Gpa = 2.9};   // no Key equivalent

  40:   

  41:  //Implicitly Typed Local Variables

  42:  var s = "Hello!";

  43:  var nums = new int[] { 1, 2, 3 };

  44:  var hero = new SuperHero() { Name = "Batman" };

  45:   

  46:  //Type Information

  47:  int x;

  48:  Console.WriteLine(x.GetType());              // System.Int32

  49:  Console.WriteLine(typeof(int));               // System.Int32

  50:  Console.WriteLine(x.GetType().Name);   // Int32

  51:   

  52:  Circle c = new Circle();

  53:  isShape = c is Shape;   // true if c is a Shape    

  54:   

  55:  isSame = Object.ReferenceEquals(o1, o2)   // true if o1 and o2 reference same object

  56:   

  57:  //Type Conversion / Casting

  58:  float d = 3.5f;

  59:  i = Convert.ToInt32(d);     // Set to 4 (rounds)

  60:  int i = (int)d;     // set to 3 (truncates decimal)    

  61:   

  62:  Shape s = new Shape();

  63:  Circle c = s as Circle;   // Returns null if type cast fails

  64:  c = (Circle)s;   // Throws InvalidCastException if type cast fails

   1:  Const MAX_STUDENTS As Integer = 25

   2:   

   3:  ' Can set to a const or var; may be initialized in a constructor

   4:  ReadOnly MIN_DIAMETER As Single = 4.93 

   1:  const int MAX_STUDENTS = 25;

   2:   

   3:  // Can set to a const or var; may be initialized in a constructor

   4:  readonly float MIN_DIAMETER = 4.93f; 

   1:  Enum Action

   2:    Start 

   3:    [Stop]   ' Stop is a reserved word

   4:    Rewind

   5:    Forward

   6:  End Enum

   7:   

   8:  Enum Status

   9:    Flunk = 50

  10:    Pass = 70

  11:    Excel = 90

  12:  End Enum

  13:   

  14:  Dim a As Action = Action.Stop

  15:  If a <> Action.Start Then _

  16:     Console.WriteLine(a.ToString & " is " & a)     ' "Stop is 1"

  17:   

  18:  Console.WriteLine(Status.Pass)     ' 70

  19:  Console.WriteLine(Status.Pass.ToString)     ' Pass

   1:  enum Action {Start, Stop, Rewind, Forward};

   2:  enum Status {Flunk = 50, Pass = 70, Excel = 90};

   3:   

   4:  Action a = Action.Stop;

   5:  if (a != Action.Start)

   6:    Console.WriteLine(a + " is " + (int) a);    // "Stop is 1"

   7:   

   8:  Console.WriteLine((int) Status.Pass);    // 70

   9:  Console.WriteLine(Status.Pass);      // Pass

   1:  'Comparison

   2:  =  <  >  <=  >=  <>

   3:   

   4:  'Arithmetic

   5:  +  -  *  /

   6:  Mod

   7:  \  (integer division)

   8:  ^  (raise to a power)

   9:   

  10:  'Assignment

  11:  =  +=  -=  *=  /=  \=  ^=  <<=  >>=  &=

  12:   

  13:  'Bitwise

  14:  And   Or   Xor   Not   <<   >>

  15:   

  16:  'Logical

  17:  AndAlso   OrElse   And   Or   Xor   Not

  18:   

  19:  'Note: AndAlso and OrElse perform short-circuit logical evaluations

  20:   

  21:  'String Concatenation

  22:  & 

   1:  //Comparison

   2:  ==  <  >  <=  >=  !=

   3:   

   4:  //Arithmetic

   5:  +  -  *  /

   6:  %  (mod)

   7:  /  (integer division if both operands are ints)

   8:  Math.Pow(x, y)

   9:   

  10:  //Assignment

  11:  =  +=  -=  *=  /=   %=  &=  |=  ^=  <<=  >>=  ++  --

  12:   

  13:  //Bitwise

  14:  &   |   ^   ~   <<   >>

  15:   

  16:  //Logical

  17:  &&   ||   &   |   ^   !

  18:   

  19:  //Note: && and || perform short-circuit logical evaluations

  20:   

  21:  //String Concatenation

  22:  +

   1:  ' Null-coalescing operator if called with 2 arguments

   2:  x = If(y, 5)   ' if y is not Nothing then x = y, else x = 5

   3:   

   4:  ' Ternary/Conditional operator (IIf evaluates 2nd and 3rd expressions)

   5:  greeting = If(age < 20, "What's up?", "Hello")

   6:   

   7:  ' One line doesn't require "End If"

   8:  If age < 20 Then greeting = "What's up?"

   9:  If age < 20 Then greeting = "What's up?" Else greeting = "Hello"

  10:   

  11:  ' Use : to put two commands on same line

  12:  If x <> 100 AndAlso y < 5 Then x *= 5 : y *= 2  

  13:   

  14:  ' Preferred

  15:  If x <> 100 AndAlso y < 5 Then

  16:    x *= 5

  17:    y *= 2

  18:  End If

  19:   

  20:  ' Use _ to break up long single line or use implicit line break

  21:  If whenYouHaveAReally < longLine And

  22:    itNeedsToBeBrokenInto2 > Lines Then _

  23:    UseTheUnderscore(charToBreakItUp)

  24:   

  25:  'If x > 5 Then

  26:    x *= y

  27:  ElseIf x = 5 OrElse y Mod 2 = 0 Then

  28:    x += y

  29:  ElseIf x < 10 Then

  30:    x -= y

  31:  Else

  32:    x /= y

  33:  End If

  34:   

  35:  Select Case color   ' Must be a primitive data type

  36:    Case "pink", "red"

  37:      r += 1

  38:    Case "blue"

  39:      b += 1

  40:    Case "green"

  41:      g += 1

  42:    Case Else

  43:      other += 1

  44:  End Select 

   1:  // Null-coalescing operator

   2:  x = y ?? 5;   // if y != null then x = y, else x = 5

   3:   

   4:  // Ternary/Conditional operator

   5:  greeting = age < 20 ? "What's up?" : "Hello";

   6:   

   7:  if (age < 20)

   8:    greeting = "What's up?";

   9:  else

  10:    greeting = "Hello";

  11:   

  12:  // Multiple statements must be enclosed in {}

  13:  if (x != 100 && y < 5) {   

  14:    x *= 5;

  15:    y *= 2;

  16:  }

  17:   

  18:   

  19:  No need for _ or : since ; is used to terminate each statement.

  20:   

  21:   

  22:   

  23:  if (x > 5)

  24:    x *= y;

  25:  else if (x == 5 || y % 2 == 0)

  26:    x += y;

  27:  else if (x < 10)

  28:    x -= y;

  29:  else

  30:    x /= y;

  31:   

  32:   

  33:   

  34:  // Every case must end with break or goto case

  35:  switch (color) {                          // Must be integer or string

  36:    case "pink":

  37:    case "red":    r++;    break;

  38:    case "blue":   b++;   break;

  39:    case "green": g++;   break;

  40:    default:    other++;   break;       // break necessary on default

  41:  } 

   1:  'Pre-test Loops:

   2:  While c < 10

   3:    c += 1

   4:  End While     

   5:   

   6:  Do Until c = 10 

   7:    c += 1

   8:  Loop

   9:   

  10:  Do While c < 10

  11:    c += 1

  12:  Loop     

  13:   

  14:  For c = 2 To 10 Step 2

  15:    Console.WriteLine(c)

  16:  Next

  17:   

  18:  'Post-test Loops:

  19:  Do 

  20:    c += 1

  21:  Loop While c < 10     

  22:   

  23:  Do 

  24:    c += 1

  25:  Loop Until c = 10

  26:   

  27:  '  Array or collection looping

  28:  Dim names As String() = {"Fred", "Sue", "Barney"}

  29:  For Each s As String In names

  30:    Console.WriteLine(s)

  31:  Next

  32:   

  33:  ' Breaking out of loops

  34:  Dim i As Integer = 0

  35:  While (True)

  36:    If (i = 5) Then Exit While

  37:    i += 1

  38:  End While

  39:   

  40:  ' Continue to next iteration

  41:  For i = 0 To 4

  42:    If i < 4 Then Continue For

  43:    Console.WriteLine(i)   ' Only prints 4

  44:  Next 

   1:  //Pre-test Loops:  

   2:   

   3:  // no "until" keyword

   4:  while (c < 10)

   5:    c++;

   6:   

   7:   

   8:  for (c = 2; c <= 10; c += 2)

   9:    Console.WriteLine(c);

  10:   

  11:   

  12:   

  13:   

  14:   

  15:   

  16:   

  17:   

  18:  //Post-test Loop:

  19:   

  20:  do

  21:    c++;

  22:  while (c < 10);

  23:   

  24:   

  25:  // Array or collection looping

  26:  string[] names = {"Fred", "Sue", "Barney"};

  27:  foreach (string s in names)

  28:    Console.WriteLine(s);

  29:   

  30:   

  31:  // Breaking out of loops

  32:  int i = 0;

  33:  while (true) {

  34:    if (i == 5)

  35:      break;

  36:    i++;

  37:  }

  38:   

  39:  // Continue to next iteration

  40:  for (i = 0; i <= 4; i++) {

  41:    if (i < 4)

  42:      continue;

  43:    Console.WriteLine(i);   // Only prints 4

  44:  } 

   1:  Dim nums() As Integer = {1, 2, 3} 

   2:  For i As Integer = 0 To nums.Length - 1

   3:    Console.WriteLine(nums(i))

   4:  Next

   5:   

   6:  ' 4 is the index of the last element, so it holds 5 elements

   7:  Dim names(4) As String

   8:  names(0) = "David"

   9:  names(5) = "Bobby"  ' Throws System.IndexOutOfRangeException

  10:   

  11:  ' Resize the array, keeping the existing values (Preserve is optional)

  12:  ReDim Preserve names(6)

  13:   

  14:  Dim twoD(rows-1, cols-1) As Single

  15:  twoD(2, 0) = 4.5

  16:   

  17:  Dim jagged()() As Integer = { _

  18:    New Integer(4) {}, New Integer(1) {}, New Integer(2) {} }

  19:  jagged(0)(4) = 5 

   1:  int[] nums = {1, 2, 3};

   2:  for (int i = 0; i < nums.Length; i++)

   3:    Console.WriteLine(nums[i]);

   4:   

   5:   

   6:  // 5 is the size of the array

   7:  string[] names = new string[5];

   8:  names[0] = "David";

   9:  names[5] = "Bobby";   // Throws System.IndexOutOfRangeException

  10:   

  11:  // Add two elements, keeping the existing values

  12:  Array.Resize(ref names, 7);

  13:   

  14:  float[,] twoD = new float[rows, cols];

  15:  twoD[2,0] = 4.5f; 

  16:   

  17:  int[][] jagged = new int[3][] {

  18:    new int[5], new int[2], new int[3] };

  19:  jagged[0][4] = 5; 

   1:  ' Popular classes in System.Collections (stored as Object)

   2:  ArrayList

   3:  Hashtable

   4:  Queue

   5:  Stack

   6:   

   7:  'Popular classes in System.Collections.Generic (stored as type T)

   8:  List(Of T)

   9:  SortedList(Of TKey, TValue)

  10:  Dictionary(Of TKey, TValue)

  11:  Queue(Of T)

  12:  Stack(Of T)

  13:   

  14:  'Popular classes in System.Collections.Concurrent (thread safe)

  15:  BlockingCollection(Of T)

  16:  ConcurrentDictionary(Of TKey, TValue)

  17:  ConcurrentQueue(Of T)

  18:  ConcurrentStack(Of T)

  19:   

  20:  'Microsoft.VisualBasic (not recommended)

  21:  Collection

  22:   

  23:   

  24:  ' Store ID and name

  25:  Dim students As New Dictionary(Of Integer, String) From

  26:  {

  27:    {123, "Bob"},

  28:    {444, "Sue"},

  29:    {555, "Jane"}

  30:  }

  31:   

  32:  students.Add(987, "Gary")

  33:  Console.WriteLine(students(444))   ' Sue

  34:   

  35:  ' Display all

  36:  For Each stu In students

  37:    Console.WriteLine(stu.Key & " = " & stu.Value)

  38:  Next

  39:   

  40:  ' Method iterator for custom iteration over a collection

  41:  Iterator Function OddNumbers(ByVal lastNum As Integer) As System.Collections.IEnumerable

  42:    For num = 1 To lastNum

  43:      If num Mod 2 = 1 Then

  44:        Yield num

  45:      End If

  46:    Next

  47:  End Function

  48:   

  49:  ' 1 3 5 7

  50:  For Each num In OddNumbers(7)

  51:    Console.Write(num & " ")

  52:  Next

   1:  // Popular classes in System.Collections (stored as Object)

   2:  ArrayList

   3:  Hashtable

   4:  Queue

   5:  Stack

   6:   

   7:  //Popular classes in System.Collections.Generic (stored as type T)

   8:  List<T>

   9:  SortedList<TKey, TValue>

  10:  Dictionary<TKey, TValue>

  11:  Queue<T>

  12:  Stack<T>

  13:   

  14:  //Popular classes in System.Collections.Concurrent (thread safe)

  15:  BlockingCollection<T>

  16:  ConcurrentDictionary<TKey, TValue>

  17:  ConcurrentQueue<T>

  18:  ConcurrentStack<T>

  19:   

  20:  //No equivalent to Microsoft.VisualBasic.Collection

  21:   

  22:   

  23:  // Store ID and name

  24:  var students = new Dictionary<int, string>

  25:  {

  26:    { 123, "Bob" },

  27:    { 444, "Sue" },

  28:    { 555, "Jane" }

  29:  };

  30:   

  31:  students.Add(987, "Gary");

  32:  Console.WriteLine(students[444]);   // Sue

  33:   

  34:  // Display all

  35:  foreach (var stu in students) {

  36:    Console.WriteLine(stu.Key + " = " + stu.Value);

  37:  }

  38:   

  39:   

  40:  // Method iterator for custom iteration over a collection

  41:  static System.Collections.Generic.IEnumerable<int> OddNumbers(int lastNum)

  42:  {

  43:    for (var num = 1; num <= lastNum; num++)

  44:      if (num % 2 == 1)

  45:        yield return num;

  46:  }

  47:   

  48:  // 1 3 5 7

  49:  foreach (double num in OddNumbers(7))

  50:  {

  51:    Console.Write(num + " ");

  52:  }

   1:  ' Pass by value (in, default), reference (in/out), and reference (out) 

   2:  Sub TestFunc(ByVal x As Integer, ByRef y As Integer, ByRef z As Integer)

   3:    x += 1

   4:    y += 1

   5:    z = 5

   6:  End Sub

   7:   

   8:  Dim a = 1, b = 1, c As Integer   ' c set to zero by default 

   9:  TestFunc(a, b, c)

  10:  Console.WriteLine("{0} {1} {2}", a, b, c)   ' 1 2 5

  11:   

  12:  ' Accept variable number of arguments

  13:  Function Sum(ByVal ParamArray nums As Integer()) As Integer

  14:    Sum = 0 

  15:    For Each i As Integer In nums

  16:      Sum += i

  17:    Next

  18:  End Function   ' Or use Return statement like C#

  19:   

  20:  Dim total As Integer = Sum(4, 3, 2, 1)   ' returns 10

  21:   

  22:  ' Optional parameters must be listed last and must have a default value

  23:  Sub SayHello(ByVal name As String, Optional ByVal prefix As String = "")

  24:    Console.WriteLine("Greetings, " & prefix & " " & name)

  25:  End Sub

  26:   

  27:  SayHello("Strangelove", "Dr.")

  28:  SayHello("Mom")

   1:  // Pass by value (in, default), reference (in/out), and reference (out)

   2:  void TestFunc(int x, ref int y, out int z) {

   3:    x++;  

   4:    y++;

   5:    z = 5;

   6:  }

   7:   

   8:  int a = 1, b = 1, c;  // c doesn't need initializing

   9:  TestFunc(a, ref b, out c);

  10:  Console.WriteLine("{0} {1} {2}", a, b, c);  // 1 2 5

  11:   

  12:  // Accept variable number of arguments

  13:  int Sum(params int[] nums) {

  14:    int sum = 0;

  15:    foreach (int i in nums)

  16:      sum += i;

  17:    return sum;

  18:  }

  19:   

  20:  int total = Sum(4, 3, 2, 1);   // returns 10

  21:   

  22:  /* C# 4.0 supports optional parameters. Previous versions required function overloading. */ 

  23:  void SayHello(string name, string prefix = "") {

  24:    Console.WriteLine("Greetings, " + prefix + " " + name);

  25:  } 

  26:   

  27:  SayHello("Strangelove", "Dr.");

  28:  SayHello("Mom"); 

   1:  'Special character constants (all also accessible from ControlChars class)

   2:  vbCrLf, vbCr, vbLf, vbNewLine

   3:  vbNullString

   4:  vbTab

   5:  vbBack

   6:  vbFormFeed

   7:  vbVerticalTab

   8:  ""

   9:   

  10:  ' String concatenation (use & or +)

  11:  Dim school As String = "Harding" & vbTab

  12:  school = school & "University"   ' school is "Harding (tab) University"

  13:  school &= "University"   ' Same thing (+= does the same)    

  14:   

  15:  ' Chars

  16:  Dim letter As Char = school.Chars(0)   ' letter is H

  17:  letter = "Z"c                                         ' letter is Z

  18:  letter = Convert.ToChar(65)                ' letter is A

  19:  letter = Chr(65)                                 ' same thing

  20:  Dim word() As Char = school.ToCharArray ' word holds Harding

  21:   

  22:  ' No string literal operator

  23:  Dim filename As String = "c:\temp\x.dat"

  24:   

  25:  ' String comparison

  26:  Dim mascot As String = "Bisons"

  27:  If (mascot = "Bisons") Then   ' true

  28:  If (mascot.Equals("Bisons")) Then   ' true

  29:  If (mascot.ToUpper().Equals("BISONS")) Then  ' true

  30:  If (mascot.CompareTo("Bisons") = 0) Then   ' true

  31:   

  32:  ' String matching with Like - Regex is more powerful

  33:  If ("John 3:16" Like "Jo[Hh]? #:*") Then   'true

  34:   

  35:  ' Substring

  36:  s = mascot.Substring(2, 3)) ' son

  37:  s = Mid("testing", 2, 3)   ' est

  38:   

  39:  ' Replacement

  40:  s = mascot.Replace("sons", "nomial")) ' s is "Binomial"

  41:   

  42:  ' Split

  43:  Dim names As String = "Michael,Dwight,Jim,Pam"

  44:  Dim parts() As String = names.Split(",".ToCharArray())   ' One name in each slot

  45:   

  46:  ' Date to string

  47:  Dim dt As New DateTime(1973, 10, 12)

  48:  Dim s As String = "My birthday: " & dt.ToString("MMM dd, yyyy")   ' Oct 12, 1973

  49:   

  50:  ' Integer to String

  51:  Dim x As Integer = 2

  52:  Dim y As String = x.ToString()     ' y is "2"

  53:   

  54:  ' String to Integer

  55:  Dim x As Integer = Convert.ToInt32("-5")     ' x is -5

  56:   

  57:  ' Mutable string

  58:  Dim buffer As New System.Text.StringBuilder("two ")

  59:  buffer.Append("three ")

  60:  buffer.Insert(0, "one ")

  61:  buffer.Replace("two", "TWO")

  62:  Console.WriteLine(buffer)         ' Prints "one TWO three" 

   1:  //Escape sequences

   2:  \r    // carriage-return

   3:  \n    // line-feed

   4:  \t    // tab

   5:  \\    // backslash

   6:  \"    // quote"

   7:   

   8:   

   9:  // String concatenation

  10:  string school = "Harding\t";

  11:  school = school + "University";   // school is "Harding (tab) University"

  12:  school += "University";   // Same thing

  13:   

  14:  // Chars

  15:  char letter = school[0];            // letter is H

  16:  letter = 'Z';                               // letter is Z

  17:  letter = Convert.ToChar(65);     // letter is A

  18:  letter = (char)65;                    // same thing

  19:  char[] word = school.ToCharArray();   // word holds Harding

  20:   

  21:  // String literal

  22:  string filename = @"c:\temp\x.dat";   // Same as "c:\\temp\\x.dat"

  23:   

  24:  // String comparison

  25:  string mascot = "Bisons";

  26:  if (mascot == "Bisons")    // true

  27:  if (mascot.Equals("Bisons"))   // true

  28:  if (mascot.ToUpper().Equals("BISONS"))   // true

  29:  if (mascot.CompareTo("Bisons") == 0)    // true

  30:   

  31:  // String matching - No Like equivalent, use Regex

  32:   

  33:   

  34:  // Substring

  35:  s = mascot.Substring(2, 3))     // son

  36:  s = "testing".Substring(1, 3);   // est (no Mid)

  37:   

  38:  // Replacement

  39:  s = mascot.Replace("sons", "nomial"))     // Binomial

  40:   

  41:  // Split

  42:  string names = "Michael,Dwight,Jim,Pam";

  43:  string[] parts = names.Split(",".ToCharArray());   // One name in each slot

  44:   

  45:  // Date to string

  46:  DateTime dt = new DateTime(1973, 10, 12);

  47:  string s = dt.ToString("MMM dd, yyyy");     // Oct 12, 1973

  48:   

  49:  // int to string

  50:  int x = 2;

  51:  string y = x.ToString();     // y is "2"

  52:  // string to int

  53:  int x = Convert.ToInt32("-5");     // x is -5

  54:   

  55:  // Mutable string

  56:  System.Text.StringBuilder buffer = new System.Text.StringBuilder("two ");

  57:  buffer.Append("three ");

  58:  buffer.Insert(0, "one ");

  59:  buffer.Replace("two", "TWO");

  60:  Console.WriteLine(buffer);     // Prints "one TWO three"

   1:   Imports System.Text.RegularExpressions

   2:   

   3:  ' Match a string pattern

   4:  Dim r As New Regex("j[aeiou]h?. \d:*", RegexOptions.IgnoreCase Or _

   5:          RegexOptions.Compiled)

   6:  If (r.Match("John 3:16").Success) Then   'true

   7:      Console.WriteLine("Match")

   8:  End If

   9:   

  10:  ' Find and remember all matching patterns

  11:  Dim s As String = "My number is 305-1881, not 305-1818."

  12:  Dim r As New Regex("(\d+-\d+)")

  13:  Dim m As Match = r.Match(s)     ' Matches 305-1881 and 305-1818

  14:  While m.Success

  15:      Console.WriteLine("Found number: " & m.Groups(1).Value & " at position " _

  16:              & m.Groups(1).Index.ToString)

  17:      m = m.NextMatch()

  18:  End While

  19:   

  20:  ' Remeber multiple parts of matched pattern

  21:  Dim r As New Regex("(\d\d):(\d\d) (am|pm)")

  22:  Dim m As Match = r.Match("We left at 03:15 pm.")

  23:  If m.Success Then

  24:      Console.WriteLine("Hour: " & m.Groups(1).ToString)       ' 03

  25:      Console.WriteLine("Min: " & m.Groups(2).ToString)         ' 15

  26:      Console.WriteLine("Ending: " & m.Groups(3).ToString)   ' pm

  27:  End If

  28:   

  29:  ' Replace all occurrances of a pattern

  30:  Dim r As New Regex("h\w+?d", RegexOptions.IgnoreCase)

  31:  Dim s As String = r.Replace("I heard this was HARD!", "easy")   ' I easy this was easy!

  32:   

  33:  ' Replace matched patterns

  34:  Dim s As String = Regex.Replace("123 < 456", "(\d+) . (\d+)", "$2 > $1")   ' 456 > 123

  35:   

  36:  ' Split a string based on a pattern

  37:  Dim names As String = "Michael, Dwight, Jim, Pam"

  38:  Dim r As New Regex(",\s*")

  39:  Dim parts() As String = r.Split(names)   ' One name in each slot 

   1:  using System.Text.RegularExpressions;

   2:   

   3:  // Match a string pattern

   4:  Regex r = new Regex(@"j[aeiou]h?. \d:*", RegexOptions.IgnoreCase |

   5:          RegexOptions.Compiled);

   6:  if (r.Match("John 3:16").Success)   // true

   7:      Console.WriteLine("Match");

   8:   

   9:   

  10:  // Find and remember all matching patterns

  11:  string s = "My number is 305-1881, not 305-1818.";

  12:  Regex r = new Regex("(\\d+-\\d+)");

  13:  // Matches 305-1881 and 305-1818

  14:  for (Match m = r.Match(s); m.Success; m = m.NextMatch())

  15:      Console.WriteLine("Found number: " + m.Groups[1] + " at position " +

  16:          m.Groups[1].Index);

  17:   

  18:   

  19:   

  20:  // Remeber multiple parts of matched pattern

  21:  Regex r = new Regex("@(\d\d):(\d\d) (am|pm)");

  22:  Match m = r.Match("We left at 03:15 pm.");

  23:  if (m.Success) {

  24:      Console.WriteLine("Hour: " + m.Groups[1]);       // 03

  25:      Console.WriteLine("Min: " + m.Groups[2]);         // 15

  26:      Console.WriteLine("Ending: " + m.Groups[3]);   // pm

  27:  }

  28:   

  29:  // Replace all occurrances of a pattern

  30:  Regex r = new Regex("h\\w+?d", RegexOptions.IgnoreCase);

  31:  string s = r.Replace("I heard this was HARD!", "easy"));   // I easy this was easy!

  32:   

  33:  // Replace matched patterns

  34:  string s = Regex.Replace("123 < 456", @"(\d+) . (\d+)", "$2 > $1");   // 456 > 123

  35:   

  36:  // Split a string based on a pattern

  37:  string names = "Michael, Dwight, Jim, Pam";

  38:  Regex r = new Regex(@",\s*");

  39:  string[] parts = r.Split(names);   // One name in each slot 

   1:  ' Throw an exception

   2:  Dim ex As New Exception("Something is really wrong.")

   3:  Throw  ex 

   4:   

   5:  ' Catch an exception

   6:  Try 

   7:    y = 0

   8:    x = 10 / y

   9:  Catch ex As Exception When y = 0 ' Argument and When is optional

  10:    Console.WriteLine(ex.Message)

  11:  Finally

  12:    Beep()

  13:  End Try

  14:   

  15:  ' Deprecated unstructured error handling

  16:  On Error GoTo MyErrorHandler

  17:  ...

  18:  MyErrorHandler: Console.WriteLine(Err.Description)

   1:  Exception up = new Exception("Something is really wrong.");

   2:  throw up;  // ha ha

   3:   

   4:  // Catch an exception

   5:  try { 

   6:    y = 0;

   7:    x = 10 / y;

   8:  }

   9:  catch (Exception ex) {   // Argument is optional, no "When" keyword 

  10:    Console.WriteLine(ex.Message);

  11:  }

  12:  finally {

  13:    Microsoft.VisualBasic.Interaction.Beep();

  14:  } 

   1:  Namespace Harding.Compsci.Graphics 

   2:    ...

   3:  End Namespace

   4:   

   5:  ' or

   6:   

   7:  Namespace Harding

   8:    Namespace Compsci

   9:      Namespace Graphics 

  10:        ...

  11:      End Namespace

  12:    End Namespace

  13:  End Namespace

  14:   

  15:  Imports Harding.Compsci.Graphics 

   1:  namespace Harding.Compsci.Graphics {

   2:    ...

   3:  }

   4:   

   5:  // or

   6:   

   7:  namespace Harding {

   8:    namespace Compsci {

   9:      namespace Graphics {

  10:        ...

  11:      }

  12:    }

  13:  }

  14:   

  15:  using Harding.Compsci.Graphics; 

   1:  ' Attribute can be applied to anything

   2:  Public Class IsTestedAttribute

   3:      Inherits Attribute

   4:  End Class

   5:   

   6:  ' Attribute can only be applied to classes or structs

   7:  <AttributeUsage(AttributeTargets.Class Or AttributeTargets.Struct)>

   8:  Public Class AuthorAttribute

   9:      Inherits Attribute

  10:   

  11:      Public Property Name As String

  12:      Public Property Version As Integer = 0

  13:   

  14:      Public Sub New(ByVal name As String)

  15:          Me.Name = name

  16:      End Sub

  17:  End Class

  18:   

  19:  <Author("Sue", Version:=3)>

  20:  Class Shape

  21:   

  22:      <IsTested()>

  23:      Sub Move()

  24:          ' Do something...

  25:      End Sub

  26:  End Class

   1:  // Attribute can be applied to anything

   2:  public class IsTestedAttribute : Attribute

   3:  {

   4:  }

   5:   

   6:  // Attribute can only be applied to classes or structs

   7:  [AttributeUsage(AttributeTargets.Class | AttributeTargets.Struct)]

   8:  public class AuthorAttribute : Attribute {

   9:   

  10:      public string Name { get; set; }

  11:      public int Version { get; set; }

  12:   

  13:      public AuthorAttribute(string name) {

  14:          Name = name;

  15:          Version = 0;

  16:      }

  17:  }

  18:   

  19:  [Author("Sue", Version = 3)]

  20:  class Shape {

  21:   

  22:      [IsTested]

  23:      void Move() {

  24:          // Do something...

  25:      }

  26:  }

   1:  'Access Modifiers

   2:  Public

   3:  Private

   4:  Friend

   5:  Protected

   6:  Protected Friend

   7:   

   8:  'Class Modifiers

   9:  MustInherit

  10:  NotInheritable

  11:   

  12:  'Method Modifiers

  13:  MustOverride

  14:  NotInheritable

  15:  Shared

  16:  Overridable

  17:   

  18:  ' All members are Shared

  19:  Module

  20:   

  21:  ' Partial classes

  22:  Partial Class Team

  23:    ...

  24:    Protected name As String

  25:    Public Overridable Sub DisplayName()

  26:      Console.WriteLine(name)

  27:    End Sub

  28:  End Class 

  29:   

  30:  ' Inheritance

  31:  Class FootballTeam

  32:    Inherits Team

  33:    ...

  34:    Public Overrides Sub DisplayName()

  35:      Console.WriteLine("** " + name + " **")

  36:    End Sub

  37:  End Class 

  38:   

  39:  ' Interface definition

  40:  Interface IAlarmClock

  41:    Sub Ring()

  42:    Property TriggerDateTime() As DateTime

  43:  End Interface

  44:   

  45:  ' Extending an interface

  46:  Interface IAlarmClock

  47:    Inherits IClock

  48:    ...

  49:  End Interface

  50:   

  51:  ' Interface implementation

  52:  Class WristWatch 

  53:    Implements IAlarmClock, ITimer

  54:   

  55:    Public Sub Ring() Implements IAlarmClock.Ring

  56:      Console.WriteLine("Wake up!")

  57:    End Sub

  58:   

  59:    Public Property TriggerDateTime As DateTime Implements IAlarmClock.TriggerDateTime

  60:    ...

  61:  End Class 

   1:  //Access Modifiers

   2:  public

   3:  private

   4:  internal

   5:  protected

   6:  protected internal

   7:   

   8:  //Class Modifiers

   9:  abstract

  10:  sealed

  11:  static

  12:   

  13:  //Method Modifiers

  14:  abstract

  15:  sealed

  16:  static

  17:  virtual

  18:   

  19:  //No Module equivalent - just use static class

  20:   

  21:  // Partial classes

  22:  partial class Team {

  23:    ...

  24:    protected string name;

  25:    public virtual void DislpayName() {

  26:      Console.WriteLine(name);

  27:  }

  28:   

  29:   

  30:  // Inheritance

  31:  class FootballTeam : Team {

  32:    ...

  33:    public override void DislpayName() {

  34:      Console.WriteLine("** " + name + " **");

  35:    }

  36:  }

  37:   

  38:   

  39:  // Interface definition

  40:  interface IAlarmClock {

  41:    void Ring();

  42:    DateTime CurrentDateTime { get; set; }

  43:  }

  44:   

  45:  // Extending an interface 

  46:  interface IAlarmClock : IClock {

  47:    ...

  48:  }

  49:   

  50:   

  51:  // Interface implementation

  52:  class WristWatch : IAlarmClock, ITimer {

  53:   

  54:    public void Ring() {

  55:      Console.WriteLine("Wake up!");

  56:    }

  57:   

  58:    public DateTime TriggerDateTime { get; set; }

  59:    ...

  60:  } 

   1:  Class SuperHero

   2:    Inherits Person

   3:   

   4:    Private powerLevel As Integer

   5:    Private name As String

   6:   

   7:    ' Default constructor

   8:    Public Sub New()

   9:      powerLevel = 0

  10:      name = "Super Bison"

  11:    End Sub

  12:   

  13:    Public Sub New(ByVal powerLevel As Integer)

  14:      Me.New("Super Bison")   ' Call other constructor

  15:      Me.powerLevel = powerLevel

  16:    End Sub

  17:   

  18:    Public Sub New(ByVal name As String)

  19:      MyBase.New(name)   ' Call base classes' constructor

  20:      Me.name = name

  21:    End Sub

  22:   

  23:    Shared Sub New()

  24:      ' Shared constructor invoked before 1st instance is created

  25:    End Sub

  26:   

  27:    Protected Overrides Sub Finalize() 

  28:     ' Destructor to free unmanaged resources

  29:      MyBase.Finalize()

  30:    End Sub

  31:  End Class

   1:  class SuperHero : Person {

   2:   

   3:    private int powerLevel;

   4:    private string name;

   5:   

   6:   

   7:    // Default constructor

   8:    public SuperHero() {

   9:      powerLevel = 0;

  10:      name = "Super Bison";

  11:    }

  12:   

  13:    public SuperHero(int powerLevel)

  14:      : this("Super Bison") {   // Call other constructor

  15:      this.powerLevel = powerLevel; 

  16:    }

  17:   

  18:    public SuperHero(string name)

  19:      : base(name) {   // Call base classes' constructor

  20:      this.name = name;

  21:    }

  22:   

  23:    static SuperHero() {

  24:      // Static constructor invoked before 1st instance is created

  25:    }

  26:   

  27:    ~SuperHero() {

  28:      // Destructor implicitly creates a Finalize method

  29:    }

  30:   

  31:  }

   1:  Dim hero As SuperHero = New SuperHero

   2:  ' or

   3:  Dim hero As New SuperHero

   4:   

   5:  With hero

   6:    .Name = "SpamMan"

   7:    .PowerLevel = 3

   8:  End With

   9:   

  10:  hero.Defend("Laura Jones")

  11:  hero.Rest()     ' Calling Shared method

  12:  ' or

  13:  SuperHero.Rest()

  14:   

  15:  Dim hero2 As SuperHero = hero  ' Both reference the same object

  16:  hero2.Name = "WormWoman"

  17:  Console.WriteLine(hero.Name)   ' Prints WormWoman

  18:   

  19:  hero = Nothing    ' Free the object

  20:   

  21:  If hero Is Nothing Then _

  22:    hero = New SuperHero

  23:   

  24:  Dim obj As Object = New SuperHero

  25:  If TypeOf obj Is SuperHero Then _

  26:    Console.WriteLine("Is a SuperHero object.")

  27:   

  28:  ' Mark object for quick disposal

  29:  Using reader As StreamReader = File.OpenText("test.txt")

  30:    Dim line As String = reader.ReadLine()

  31:    While Not line Is Nothing

  32:      Console.WriteLine(line)

  33:      line = reader.ReadLine()

  34:    End While

  35:  End Using 

   1:  SuperHero hero = new SuperHero();

   2:   

   3:   

   4:   

   5:  // No "With" but can use object initializers

   6:  SuperHero hero = new SuperHero() { Name = "SpamMan", PowerLevel = 3 };

   7:   

   8:  hero.Defend("Laura Jones");

   9:  SuperHero.Rest();   // Calling static method

  10:   

  11:   

  12:   

  13:  SuperHero hero2 = hero;   // Both reference the same object

  14:  hero2.Name = "WormWoman";

  15:  Console.WriteLine(hero.Name);   // Prints WormWoman

  16:   

  17:  hero = null ;   // Free the object

  18:   

  19:  if (hero == null)

  20:    hero = new SuperHero();

  21:   

  22:  Object obj = new SuperHero(); 

  23:  if (obj is SuperHero)

  24:    Console.WriteLine("Is a SuperHero object.");

  25:  // Mark object for quick disposal

  26:  using (StreamReader reader = File.OpenText("test.txt")) {

  27:    string line;

  28:    while ((line = reader.ReadLine()) != null)

  29:      Console.WriteLine(line);

  30:  } 

   1:  Structure Student

   2:    Public name As String

   3:    Public gpa As Single

   4:   

   5:    Public Sub New(ByVal name As String, ByVal gpa As Single)

   6:      Me.name = name

   7:      Me.gpa = gpa

   8:    End Sub

   9:  End Structure

  10:   

  11:  Dim stu As Student = New Student("Bob", 3.5)

  12:  Dim stu2 As Student = stu  

  13:   

  14:  stu2.name = "Sue"

  15:  Console.WriteLine(stu.name)    ' Prints Bob

  16:  Console.WriteLine(stu2.name)  ' Prints Sue

   1:  struct Student {

   2:    public string name;

   3:    public float gpa;

   4:   

   5:    public Student(string name, float gpa) {

   6:      this.name = name;

   7:      this.gpa = gpa;

   8:    }

   9:  }

  10:   

  11:  Student stu = new Student("Bob", 3.5f);

  12:  Student stu2 = stu;  

  13:   

  14:  stu2.name = "Sue";

  15:  Console.WriteLine(stu.name);    // Prints Bob

  16:  Console.WriteLine(stu2.name);   // Prints Sue

   1:  ' Auto-implemented properties are new to VB10

   2:  Public Property Name As String

   3:  Public Property Size As Integer = -1     ' Default value, Get and Set both Public

   4:   

   5:  ' Traditional property implementation

   6:  Private mName As String

   7:  Public Property Name() As String

   8:      Get

   9:          Return mName

  10:      End Get

  11:      Set(ByVal value As String)

  12:          mName = value

  13:      End Set

  14:  End Property

  15:   

  16:  ' Read-only property

  17:  Private mPowerLevel As Integer

  18:  Public ReadOnly Property PowerLevel() As Integer

  19:      Get

  20:          Return mPowerLevel

  21:      End Get

  22:  End Property

  23:   

  24:  ' Write-only property

  25:  Private mHeight As Double

  26:  Public WriteOnly Property Height() As Double

  27:      Set(ByVal value As Double)

  28:          mHeight = If(value < 0, mHeight = 0, mHeight = value)

  29:      End Set

  30:  End Property 

   1:   // Auto-implemented properties

   2:  public string Name { get; set; }

   3:  public int Size { get; protected set; }     // Set default value in constructor

   4:   

   5:  // Traditional property implementation

   6:  private string name;

   7:  public string Name {

   8:    get {

   9:      return name;

  10:    }

  11:    set {

  12:      name = value;

  13:    }

  14:  }

  15:   

  16:  // Read-only property

  17:  private int powerLevel;

  18:  public int PowerLevel {

  19:    get {

  20:      return powerLevel;

  21:    }

  22:  }

  23:   

  24:  // Write-only property

  25:  private double height;

  26:  public double Height {

  27:    set {

  28:      height = value < 0 ? 0 : value;

  29:    }

  30:  } 

   1:   ' Enforce accepted data type at compile-time

   2:  Dim numbers As New List(Of Integer)

   3:  numbers.Add(2)

   4:  numbers.Add(4)

   5:  DisplayList(Of Integer)(numbers)

   6:   

   7:  ' Subroutine can display any type of List

   8:  Sub DisplayList(Of T)(ByVal list As List(Of T))

   9:      For Each item As T In list

  10:          Console.WriteLine(item)

  11:      Next

  12:  End Sub

  13:   

  14:  ' Class works on any data type

  15:  Class SillyList(Of T)

  16:      Private list(10) As T

  17:      Private rand As New Random

  18:   

  19:      Public Sub Add(ByVal item As T)

  20:          list(rand.Next(10)) = item

  21:      End Sub

  22:   

  23:      Public Function GetItem() As T

  24:          Return list(rand.Next(10))

  25:      End Function

  26:  End Class

  27:   

  28:  ' Limit T to only types that implement IComparable

  29:  Function Maximum(Of T As IComparable)(ByVal ParamArray items As T()) As T

  30:      Dim max As T = items(0)

  31:      For Each item As T In items

  32:          If item.CompareTo(max) > 0 Then max = item

  33:      Next

  34:      Return max

  35:  End Function

   1:   // Enforce accepted data type at compile-time

   2:  List<int> numbers = new List<int>();

   3:  numbers.Add(2);

   4:  numbers.Add(4);

   5:  DisplayList<int>(numbers);

   6:   

   7:  // Function can display any type of List

   8:  void DisplayList<T>(List<T> list) {

   9:      foreach (T item in list)

  10:          Console.WriteLine(item);

  11:  }

  12:   

  13:  // Class works on any data type

  14:  class SillyList<T> {

  15:      private T[] list = new T[10];

  16:      private Random rand = new Random();

  17:   

  18:      public void Add(T item) {

  19:          list[rand.Next(10)] = item;

  20:      }

  21:   

  22:      public T GetItem() {

  23:          return list[rand.Next(10)];

  24:      }

  25:  }

  26:   

  27:  // Limit T to only types that implement IComparable

  28:  T Maximum<T>(params T[] items) where T : IComparable<T> {

  29:      T max = items[0];

  30:      foreach (T item in items)

  31:          if (item.CompareTo(max) > 0)

  32:              max = item;

  33:      return max;

  34:  }

   1:  Delegate Sub MsgArrivedEventHandler(ByVal message As String)

   2:   

   3:  Event MsgArrivedEvent As MsgArrivedEventHandler

   4:   

   5:  ' or to define an event which declares a delegate implicitly

   6:  Event MsgArrivedEvent(ByVal message As String)

   7:   

   8:  AddHandler MsgArrivedEvent, AddressOf My_MsgArrivedCallback

   9:  ' Won't throw an exception if obj is Nothing

  10:  RaiseEvent MsgArrivedEvent("Test message")

  11:  RemoveHandler MsgArrivedEvent, AddressOf My_MsgArrivedCallback

  12:   

  13:  Imports System.Windows.Forms

  14:   

  15:  Dim WithEvents MyButton As Button   ' WithEvents can't be used on local variable

  16:  MyButton = New Button

  17:   

  18:  Sub MyButton_Click(ByVal sender As System.Object, _

  19:    ByVal e As System.EventArgs) Handles MyButton.Click

  20:    MessageBox.Show(Me, "Button was clicked", "Info", _

  21:      MessageBoxButtons.OK, MessageBoxIcon.Information)

  22:  End Sub

   1:  delegate void MsgArrivedEventHandler(string message);

   2:   

   3:  event MsgArrivedEventHandler MsgArrivedEvent;

   4:   

   5:  // Delegates must be used with events in C#

   6:   

   7:   

   8:  MsgArrivedEvent += new MsgArrivedEventHandler(My_MsgArrivedEventCallback);

   9:  MsgArrivedEvent("Test message");    // Throws exception if obj is null

  10:  MsgArrivedEvent -= new MsgArrivedEventHandler(My_MsgArrivedEventCallback);

  11:   

  12:   

  13:   

  14:  using System.Windows.Forms;

  15:   

  16:  Button MyButton = new Button(); 

  17:  MyButton.Click += new System.EventHandler(MyButton_Click);

  18:   

  19:  void MyButton_Click(object sender, System.EventArgs e) {

  20:    MessageBox.Show(this, "Button was clicked", "Info",

  21:      MessageBoxButtons.OK, MessageBoxIcon.Information);

  22:  }

   1:   Delegate Sub HelloDelegate(ByVal s As String)

   2:   

   3:  Sub SayHello(ByVal s As String)

   4:    Console.WriteLine("Hello, " & s)

   5:  End Sub

   6:  ' Create delegate that calls SayHello

   7:  Dim hello As HelloDelegate = AddressOf SayHello

   8:  hello("World")   ' Or hello.Invoke("World")

   9:   

  10:  ' Use lambda expression (anonymous method) instead of a delegate

  11:  Dim hello2 = Sub(x) Console.WriteLine("Hello, " & x)

  12:  hello2("World")

  13:   

  14:   

  15:   

  16:   

  17:   

  18:   

  19:  ' Use Func(Of T, TResult) delegate to call Uppercase

  20:  Dim convert As Func(Of String, String) = AddressOf Uppercase

  21:  Console.WriteLine(convert("test"))

  22:   

  23:  Function Uppercase(s As String) As String

  24:    Return s.ToUpper

  25:  End Function

  26:   

  27:  ' Declare and invoke lambda expression

  28:  Console.WriteLine((Function(num As Integer) num + 1)(2))

  29:   

  30:  ' Pass lambda expression as an argument

  31:  TestValues(Function(x, y) x Mod y = 0)

  32:   

  33:  Sub TestValues(ByVal f As Func(Of Integer, Integer, Boolean))

  34:    If f(8, 4) Then

  35:      Console.WriteLine("true")

  36:    Else

  37:      Console.WriteLine("false")

  38:    End If

  39:  End Sub 

   1:   delegate void HelloDelegate(string s);

   2:   

   3:  void SayHello(string s) {

   4:    Console.WriteLine("Hello, " + s);

   5:  }

   6:   

   7:  // C# 1.0 delegate syntax with named method

   8:  HelloDelegate hello = new HelloDelegate(SayHello);

   9:  hello("World");   // Or hello.Invoke("World");

  10:   

  11:  // C# 2.0 delegate syntax with anonymous method

  12:  HelloDelegate hello2 = delegate(string s) {

  13:    Console.WriteLine("Hello, " + s);

  14:  };

  15:  hello2("World");

  16:   

  17:  // C# 3.0 delegate syntax with lambda expression

  18:  HelloDelegate hello3 = s => { Console.WriteLine("Hello, " + s); };

  19:  hello3("World");

  20:   

  21:  // Use Func<in T, out TResult> delegate to call Uppercase

  22:  Func<string, string> convert = Uppercase;

  23:  Console.WriteLine(convert("test"));

  24:   

  25:  string Uppercase(string s) {

  26:    return s.ToUpper();

  27:  }

  28:   

  29:  // Declare and invoke Func using a lambda expression

  30:  Console.WriteLine(new Func<int, int>(num => num + 1)(2));

  31:   

  32:  // Pass lamba expression as an argument

  33:  TestValues((x, y) => x % y == 0);

  34:   

  35:  void TestValues(Func<int, int, bool> f) {

  36:    if (f(8, 4))

  37:      Console.WriteLine("true");

  38:    else

  39:      Console.WriteLine("false");

  40:  } 

   1:   Imports System.Runtime.CompilerServices

   2:   

   3:  Module StringExtensions

   4:    <Extension()>

   5:    Public Function VowelCount(ByVal s As String) As Integer

   6:      Return s.Count(Function(c) "aeiou".Contains(Char.ToLower(c)))

   7:    End Function

   8:  End Module

   9:   

  10:  ' Using the extension method

  11:  Console.WriteLine("This is a test".VowelCount) 

   1:   public static class StringExtensions {

   2:    public static int VowelCount(this string s) {

   3:      return s.Count(c => "aeiou".Contains(Char.ToLower(c)));

   4:    }

   5:  }

   6:   

   7:   

   8:   

   9:  // Using the extension method

  10:  Console.WriteLine("This is a test".VowelCount()); 

   1:  Dim nums() As Integer = {5, 8, 2, 1, 6}

   2:   

   3:  ' Get all numbers in the array above 4

   4:  Dim results = From n In nums

   5:                    Where n > 4

   6:                    Select n

   7:   

   8:  ' Same thing using lamba expression

   9:  results = nums.Where(Function(n) n > 4)

  10:   

  11:  ' Displays 5 8 6

  12:  For Each n As Integer In results

  13:      Console.Write(n & " ")

  14:  Next

  15:   

  16:  Console.WriteLine(results.Count())     ' 3

  17:  Console.WriteLine(results.First())     ' 5

  18:  Console.WriteLine(results.Last())     ' 6

  19:  Console.WriteLine(results.Average())     ' 6.33333

  20:   

  21:  results = results.Intersect({5, 6, 7})     ' 5 6

  22:  results = results.Concat({5, 1, 5})     ' 5 6 5 1 5

  23:  results = results.Distinct()     ' 5 6 1

  24:   

  25:  Dim Students() As Student = {

  26:      New Student With {.Name = "Bob", .Gpa = 3.5},

  27:      New Student With {.Name = "Sue", .Gpa = 4.0},

  28:      New Student With {.Name = "Joe", .Gpa = 1.9}

  29:  }

  30:   

  31:  ' Get a list of students ordered by Gpa with Gpa >= 3.0

  32:  Dim goodStudents = From s In Students

  33:              Where s.Gpa >= 3.0

  34:              Order By s.Gpa Descending

  35:              Select s

  36:   

  37:  Console.WriteLine(goodStudents.First.Name)     ' Sue

   1:  int[] nums = { 5, 8, 2, 1, 6 };

   2:   

   3:  // Get all numbers in the array above 4

   4:  var results = from n in nums

   5:                  where n > 4

   6:                  select n;

   7:   

   8:  // Same thing using lamba expression

   9:  results = nums.Where(n => n > 4);

  10:   

  11:  // Displays 5 8 6

  12:  foreach (int n in results)

  13:      Console.Write(n + " ");

  14:   

  15:   

  16:  Console.WriteLine(results.Count());     // 3

  17:  Console.WriteLine(results.First());     // 5

  18:  Console.WriteLine(results.Last());     // 6

  19:  Console.WriteLine(results.Average());     // 6.33333

  20:   

  21:  results = results.Intersect(new[] {5, 6, 7});     // 5 6

  22:  results = results.Concat(new[] {5, 1, 5});     // 5 6 5 1 5

  23:  results = results.Distinct();     // 5 6 1

  24:   

  25:  Student[] Students = {

  26:      new Student{ Name = "Bob", Gpa = 3.5 },

  27:      new Student{ Name = "Sue", Gpa = 4.0 },

  28:      new Student{ Name = "Joe", Gpa = 1.9 }

  29:  };

  30:   

  31:  // Get a list of students ordered by Gpa with Gpa >= 3.0

  32:  var goodStudents = from s in Students

  33:              where s.Gpa >= 3.0

  34:              orderby s.Gpa descending

  35:              select s;

  36:   

  37:  Console.WriteLine(goodStudents.First().Name);     // Sue

   1:  'Implicit expression    

   2:  @name Hello, <b>@name.</b> 

   3:   

   4:  'Explicit expression    

   5:  @(5+5) Hello, @name. Your age is: <b>@(5+5).</b> 

   6:   

   7:  'Unencoded expression    

   8:  @Html.Raw(name) Hello, <b>@Html.Raw(name).</b> 

   9:   

  10:  'Multi-statement code blocks    

  11:  @Code

  12:          /* VB.NET Code goes here */

  13:  End Code 

  14:  @Code

  15:      Dim greeting = "Hello, world!"

  16:      For i = 1 To 3

  17:          @<p>@greeting (@i)</p>

  18:          Next i

  19:  End Code

  20:   

  21:  'Plain text inside a code block    

  22:  @Code

  23:      @:Plain text goes here

  24:  End Code 

  25:  @If IsPost Then

  26:      Dim text = "Code goes here..."

  27:      @:Plain text goes here...

  28:  End If

  29:   

  30:  'Plain text inside a code block (alternative)    

  31:  @<text>Plain text goes here...</text> 

  32:  @If IsPost Then

  33:      Dim text = "Code goes here..."

  34:      @<text>Plain text goes here...</text>

  35:  End If 

  36:   

  37:  'Server-side comment    

  38:  @*

  39:      Here's a Razor server-side comment

  40:      It won't be rendered to the browser

  41:      It can span multiple lines

  42:  *@

  43:   

  44:  'Conditional attribute (New in MVC 4)    

  45:  <div style="@divStyle">Hello, world!</div> 

  46:  @Code

  47:      Dim divStyle As String

  48:      If Request.QueryString("style") IsNot Nothing Then

  49:          divStyle = "background-color: yellow;"

  50:      End If

  51:  End Code

  52:  <div style="@divStyle">Hello, world!</div> 

   1:  //Implicit expression    

   2:  @name Hello, <b>@name.</b> 

   3:   

   4:  //Explicit expression    

   5:  @(5+5) Hello, @name. Your age is: <b>@(5+5).</b> 

   6:   

   7:  //Unencoded expression    

   8:  @Html.Raw(name) Hello, <b>@Html.Raw(name).</b> 

   9:   

  10:  //Multi-statement code blocks    

  11:  @{

  12:          /* C# Code goes here */

  13:  } 

  14:  @{

  15:      var greeting = "Hello, world!";

  16:      for(int i = 1; i <= 3; i++)

  17:      {

  18:          <p>@greeting (@i)</p>

  19:      }

  20:  }

  21:   

  22:  //Plain text inside a code block    

  23:  @:Plain text goes here... 

  24:  @if(isTrue)

  25:  {

  26:      var text = "Code goes here...";

  27:      @:Plain text goes here...

  28:  } 

  29:   

  30:  //Plain text inside a code block (alternative)    

  31:  <text>Plain text goes here...</text> 

  32:  @if(isTrue)

  33:  {

  34:      var text = "Code goes here...";

  35:      <text>Plain text goes here...</text>

  36:  } 

  37:   

  38:  //Server-side comment

  39:  @*

  40:      Here's a Razor server-side comment

  41:      It won't be rendered to the browser

  42:      It can span multiple lines

  43:  *@ 

  44:   

  45:  //Conditional attribute (New in MVC 4)     

  46:  <div style="@divStyle">Hello, world!</div>

  47:  @{

  48:      string divStyle = null;

  49:      if(Request.QueryString["style"] != null)

  50:      {

  51:          divStyle = "background-color: yellow;";

  52:      }

  53:  }

  54:  <div style="@divStyle">Hello, world!</div>