VB.NET

Program Structure

C#

Imports System 

Namespace Hello

   Class HelloWorld 

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

         Dim name As String = "VB.NET" 

         'See if an argument was passed from the command line

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

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

      End Sub 

   End Class 

End Namespace

using System; 

namespace Hello {

   public class HelloWorld {

      public static void Main(string[] args) {

         string name = "C#";

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

         if (args.Length == 1)

            name = args[0];

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

      }

   }

}

VB.NET

Comments

C#

' Single line only

REM Single line only

''' <summary>XML comments</summary>

// Single line

/* Multiple

    line  */

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

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

VB.NET

Data Types

C#

Value Types

Boolean

Byte, SByte

Char

Short, UShort, Integer, UInteger, Long, ULong

Single, Double

Decimal

Date   (alias of System.DateTime)

structures

enumerations

Reference Types

Object

String

arrays

delegates

Initializing

Dim correct As Boolean = True

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

Dim person As Object = Nothing

Dim name As String = "Dwight"

Dim grade As Char = "B"c

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

Dim amount As Decimal = 35.99@

Dim gpa As Single = 2.9!

Dim pi As Double = 3.14159265

Dim lTotal As Long = 123456L

Dim sTotal As Short = 123S

Dim usTotal As UShort = 123US

Dim uiTotal As UInteger = 123UI

Dim ulTotal As ULong = 123UL

Nullable Types

Dim x? As Integer = Nothing

Anonymous Types

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

Dim stu2 = New With {

Key .Name = "Bob", .Gpa = 2.9}

Implicitly Typed Local Variables

Dim s = "Hello!"

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

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

Type Information

Dim x As Integer 

Console.WriteLine(x.GetType())          ' Prints System.Int32 

Console.WriteLine(GetType(Integer))   ' Prints System.Int32 

Console.WriteLine(TypeName(x))        ' Prints Integer 

Dim c as New Circle

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

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

Type Conversion / Casting

Dim d As Single = 3.5 

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

i = CInt(d)  ' same result as CType

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

Dim s As New Shape

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

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

Value Types

bool

byte, sbyte

char

short, ushort, int, uint, long, ulong

float, double

decimal

DateTime   (not a built-in C# type)

structs

enumerations

Reference Types

object

string

arrays

delegates

Initializing

bool correct = true;

byte b = 0x2A;   // hex

object person = null;

string name = "Dwight";

char grade = 'B';

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

decimal amount = 35.99m;

float gpa = 2.9f;

double pi = 3.14159265;   // or 3.14159265D

long lTotal = 123456L;

short sTotal = 123;

ushort usTotal = 123;

uint uiTotal = 123;   // or 123U

ulong ulTotal = 123;   // or 123UL

Nullable Types

int? x = null;

Anonymous Types

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

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

Implicitly Typed Local Variables

var s = "Hello!";

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

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

Type Information

int x;

Console.WriteLine(x.GetType());              // Prints System.Int32

Console.WriteLine(typeof(int));               // Prints System.Int32 

Console.WriteLine(x.GetType().Name);   // prints Int32 

Circle c = new Circle();

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

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

Type Conversion / Casting 

float d = 3.5f; 

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

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

Shape s = new Shape();

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

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

VB.NET

Constants

C#

Const MAX_STUDENTS As Integer = 25

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

ReadOnly MIN_DIAMETER As Single = 4.93

const int MAX_STUDENTS = 25;

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

readonly float MIN_DIAMETER = 4.93f;

VB.NET

Enumerations

C#

Enum Action 

  Start 

  [Stop]   ' Stop is a reserved word

  Rewind 

  Forward 

End Enum 

Enum Status 

  Flunk = 50 

  Pass = 70 

  Excel = 90 

End Enum

Dim a As Action = Action.Stop 

If a <> Action.Start Then _ 

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

Console.WriteLine(Status.Pass)     ' Prints 70 

Console.WriteLine(Status.Pass.ToString())     ' Prints Pass

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

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

Action a = Action.Stop;

if (a != Action.Start)

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

Console.WriteLine((int) Status.Pass);    // Prints 70 

Console.WriteLine(Status.Pass);      // Prints Pass

VB.NET

Operators

C#

Comparison

=  <  >  <=  >=  <>

Arithmetic

+  -  *  /

Mod

\  (integer division)

^  (raise to a power)

Assignment

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

Bitwise

And   Or   Xor   Not   <<   >>

Logical

AndAlso   OrElse   And   Or   Xor   Not

Note: AndAlso and OrElse perform short-circuit logical evaluations

String Concatenation

&

Comparison

==  <  >  <=  >=  !=

Arithmetic

+  -  *  /

%  (mod)

/  (integer division if both operands are ints)

Math.Pow(x, y)

Assignment

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

Bitwise

&   |   ^   ~   <<   >>

Logical

&&   ||   &   |   ^   !

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

String Concatenation

+

VB.NET

Choices

C#

' Null-coalescing operator if called with 2 arguments

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

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

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

' One line doesn't require "End If"

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

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

' Use : to put two commands on same line

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

' Preferred

If x <> 100 AndAlso y < 5 Then

  x *= 5 

  y *= 2

End If

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

If whenYouHaveAReally < longLine And 

  itNeedsToBeBrokenInto2 > Lines Then _

  UseTheUnderscore(charToBreakItUp)

'If x > 5 Then 

  x *= y 

ElseIf x = 5 OrElse y Mod 2 = 0 Then 

  x += y 

ElseIf x < 10 Then 

  x -= y 

Else 

  x /= y 

End If

Select Case color   ' Must be a primitive data type

  Case "pink", "red"

    r += 1 

  Case "blue" 

    b += 1 

  Case "green" 

    g += 1 

  Case Else 

    other += 1 

End Select

// Null-coalescing operator

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

// Ternary/Conditional operator

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

if (age < 20)

  greeting = "What's up?";

else

  greeting = "Hello";

// Multiple statements must be enclosed in {}

if (x != 100 && y < 5) {   

  x *= 5;

  y *= 2;

}

 

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

if (x > 5) 

  x *= y; 

else if (x == 5 || y % 2 == 0) 

  x += y; 

else if (x < 10) 

  x -= y; 

else 

  x /= y;

// Every case must end with break or goto case 

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

  case "pink":

  case "red":    r++;    break; 

  case "blue":   b++;   break;

  case "green": g++;   break;

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

}

VB.NET

Loops

C#

Pre-test Loops:
While c < 10    c += 1  End While	Do Until c = 10    c += 1  Loop
Do While c < 10    c += 1  Loop	For c = 2 To 10 Step 2    Console.WriteLine(c)  Next
Post-test Loops:
Do    c += 1  Loop While c < 10	Do    c += 1  Loop Until c = 10

'  Array or collection looping

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

For Each s As String In names 

  Console.WriteLine(s) 

Next

' Breaking out of loops

Dim i As Integer = 0

While (True)

  If (i = 5) Then Exit While

  i += 1

End While 

' Continue to next iteration

For i = 0 To 4

  If i < 4 Then Continue For

  Console.WriteLine(i)   ' Only prints 4

Next

Pre-test Loops:  

// no "until" keyword

while (c < 10) 

  c++;

for (c = 2; c <= 10; c += 2) 

  Console.WriteLine(c);

Post-test Loop:

do 

  c++; 

while (c < 10);

// Array or collection looping

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

foreach (string s in names)

  Console.WriteLine(s);

// Breaking out of loops

int i = 0;

while (true) {

  if (i == 5)

    break;

  i++;

}

// Continue to next iteration

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

  if (i < 4)

    continue;

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

}

VB.NET

Arrays

C#

Dim nums() As Integer = {1, 2, 3} 

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

  Console.WriteLine(nums(i)) 

Next 

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

Dim names(4) As String 

names(0) = "David"

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

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

ReDim Preserve names(6)

Dim twoD(rows-1, cols-1) As Single 

twoD(2, 0) = 4.5

Dim jagged()() As Integer = { _ 

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

jagged(0)(4) = 5

int[] nums = {1, 2, 3};

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

  Console.WriteLine(nums[i]);

// 5 is the size of the array

string[] names = new string[5];

names[0] = "David";

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

// Add two elements, keeping the existing values

Array.Resize(ref names, 7);

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

twoD[2,0] = 4.5f; 

int[][] jagged = new int[3][] { 

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

jagged[0][4] = 5;

VB.NET

Functions

C#

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

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

  x += 1

  y += 1 

  z = 5 

End Sub

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

TestFunc(a, b, c) 

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

' Accept variable number of arguments 

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

  Sum = 0  

  For Each i As Integer In nums 

    Sum += i 

  Next 

End Function   ' Or use Return statement like C#

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

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

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

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

End Sub

SayHello("Strangelove", "Dr.")

SayHello("Mom")

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

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

  x++;  

  y++;

  z = 5;

}

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

TestFunc(a, ref b, out c);

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

// Accept variable number of arguments

int Sum(params int[] nums) {

  int sum = 0;

  foreach (int i in nums)

    sum += i;

  return sum;

}

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

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

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

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

} 

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

SayHello("Mom");

VB.NET

Strings

C#

Special character constants (all also accessible from ControlChars class)

vbCrLf, vbCr, vbLf, vbNewLine 

vbNullString 

vbTab 

vbBack 

vbFormFeed 

vbVerticalTab

""

' String concatenation (use & or +) 

Dim school As String = "Harding" & vbTab

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

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

' Chars

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

letter = "Z"c                                         ' letter is Z 

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

letter = Chr(65)                                 ' same thing 

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

' No string literal operator 

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

' String comparison

Dim mascot As String = "Bisons"

If (mascot = "Bisons") Then   ' true

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

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

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

' String matching with Like - Regex is more powerful

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

' Substring

s = mascot.Substring(2, 3)) ' s is "son"

' Replacement

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

' Split

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

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

' Date to string

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

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

' Integer to String

Dim x As Integer = 2

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

' String to Integer

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

' Mutable string 

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

buffer.Append("three ")

buffer.Insert(0, "one ")

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

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

Escape sequences

\r    // carriage-return

\n    // line-feed

\t    // tab

\\    // backslash

\"    // quote 

// String concatenation

string school = "Harding\t";

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

school += "University";   // Same thing

// Chars

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

letter = 'Z';                               // letter is Z 

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

letter = (char)65;                    // same thing 

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

// String literal 

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

// String comparison

string mascot = "Bisons"; 

if (mascot == "Bisons")    // true

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

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

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

// String matching - No Like equivalent, use Regex

// Substring

s = mascot.Substring(2, 3))     // s is "son"

// Replacement

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

// Split

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

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

// Date to string

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

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

// int to string

int x = 2;

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

// string to int

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

// Mutable string 

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

buffer.Append("three "); 

buffer.Insert(0, "one "); 

buffer.Replace("two", "TWO"); 

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

VB.NET

Regular Expressions

C#

Imports System.Text.RegularExpressions

' Match a string pattern

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

        RegexOptions.Compiled)

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

    Console.WriteLine("Match")

End If

' Find and remember all matching patterns

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

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

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

While m.Success

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

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

    m = m.NextMatch() 

End While

' Remeber multiple parts of matched pattern

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

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

If m.Success Then

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

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

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

End If

' Replace all occurrances of a pattern

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

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

' Replace matched patterns

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

' Split a string based on a pattern

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

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

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

using System.Text.RegularExpressions;

// Match a string pattern 

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

        RegexOptions.Compiled);

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

    Console.WriteLine("Match");

// Find and remember all matching patterns

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

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

// Matches 305-1881 and 305-1818

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

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

        m.Groups[1].Index);

// Remeber multiple parts of matched pattern

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

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

if (m.Success) {

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

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

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

}

// Replace all occurrances of a pattern

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

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

// Replace matched patterns

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

// Split a string based on a pattern

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

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

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

VB.NET

Exception Handling

C#

' Throw an exception

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

Throw  ex 

' Catch an exception

Try 

  y = 0

  x = 10 / y

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

  Console.WriteLine(ex.Message) 

Finally 

  Beep() 

End Try

' Deprecated unstructured error handling

On Error GoTo MyErrorHandler

...

MyErrorHandler: Console.WriteLine(Err.Description)

// Throw an exception

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

throw up;  // ha ha

// Catch an exception

try { 

  y = 0; 

  x = 10 / y; 

} 

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

  Console.WriteLine(ex.Message); 

} 

finally { 

  Microsoft.VisualBasic.Interaction.Beep(); 

}

VB.NET

Namespaces

C#

Namespace Harding.Compsci.Graphics 

  ...

End Namespace

' or

Namespace Harding 

  Namespace Compsci 

    Namespace Graphics 

      ...

    End Namespace 

  End Namespace 

End Namespace

Imports Harding.Compsci.Graphics

namespace Harding.Compsci.Graphics {

  ...

}

// or

namespace Harding {

  namespace Compsci {

    namespace Graphics {

      ...

    }

  }

}

using Harding.Compsci.Graphics;

VB.NET

Classes & Interfaces

C#

Access Modifiers 

Public

Private

Friend

Protected

Protected Friend

Class Modifiers

MustInherit

NotInheritable

Method Modifiers 

MustOverride

NotInheritable

Shared

Overridable

' All members are Shared

Module

' Partial classes

Partial Class Competition

  ...

End Class 

' Inheritance

Class FootballGame

  Inherits Competition

  ...

End Class 

' Interface definition

Interface IAlarmClock

  Sub Ring()

  Property TriggerDateTime() As DateTime

End Interface

' Extending an interface

Interface IAlarmClock 

  Inherits IClock

  ...

End Interface

' Interface implementation

Class WristWatch 

  Implements IAlarmClock, ITimer

  Public Sub Ring() Implements IAlarmClock.Ring

    Console.WriteLine("Wake up!")

  End Sub

  Public Property TriggerDateTime As DateTime Implements IAlarmClock.TriggerDateTime

  ...

End Class 

Access Modifiers 

public

private

internal

protected

protected internal

Class Modifiers 

abstract

sealed

static

Method Modifiers 

abstract

sealed

static

virtual

No Module equivalent - just use static class

// Partial classes

partial class Competition {

  ...

}

// Inheritance

class FootballGame : Competition {

  ...

}

// Interface definition

interface IAlarmClock {

  void Ring(); 

  DateTime CurrentDateTime { get; set; }

}

// Extending an interface 

interface IAlarmClock : IClock {

  ...

}

// Interface implementation

class WristWatch : IAlarmClock, ITimer {

  public void Ring() {

    Console.WriteLine("Wake up!");

  }

  public DateTime TriggerDateTime { get; set; }

  ...

}

VB.NET

Constructors & Destructors

C#

Class SuperHero

  Inherits Person

  Private powerLevel As Integer

  Private name As String

  ' Default constructor

  Public Sub New() 

    powerLevel = 0

    name = "Super Bison" 

  End Sub 

  Public Sub New(ByVal powerLevel As Integer) 

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

    Me.powerLevel = powerLevel 

  End Sub

  Public Sub New(ByVal name As String) 

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

    Me.name = name

  End Sub

  Shared Sub New()

    ' Shared constructor invoked before 1st instance is created

  End Sub

  Protected Overrides Sub Finalize() 

   ' Destructor to free unmanaged resources 

    MyBase.Finalize() 

  End Sub

End Class

class SuperHero : Person {

  private int powerLevel;

  private string name;

  // Default constructor

  public SuperHero() {

    powerLevel = 0;

    name = "Super Bison";

  }

  public SuperHero(int powerLevel) 

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

    this.powerLevel = powerLevel; 

  }

  public SuperHero(string name)

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

    this.name = name;

  }

  static SuperHero() {

    // Static constructor invoked before 1st instance is created

  }

  ~SuperHero() {

    // Destructor implicitly creates a Finalize method

  }

}

VB.NET

Using Objects

C#

Dim hero As SuperHero = New SuperHero

' or

Dim hero As New SuperHero

With hero 

  .Name = "SpamMan" 

  .PowerLevel = 3 

End With 

hero.Defend("Laura Jones") 

hero.Rest()     ' Calling Shared method

' or

SuperHero.Rest()

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

hero2.Name = "WormWoman" 

Console.WriteLine(hero.Name)   ' Prints WormWoman

hero = Nothing    ' Free the object

If hero Is Nothing Then _ 

  hero = New SuperHero

Dim obj As Object = New SuperHero 

If TypeOf obj Is SuperHero Then _

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

' Mark object for quick disposal

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

  Dim line As String = reader.ReadLine()

  While Not line Is Nothing

    Console.WriteLine(line)

    line = reader.ReadLine()

  End While

End Using

SuperHero hero = new SuperHero(); 

// No "With" but can use object initializers

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

hero.Defend("Laura Jones");

SuperHero.Rest();   // Calling static method

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

hero2.Name = "WormWoman"; 

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

hero = null ;   // Free the object

if (hero == null)

  hero = new SuperHero();

Object obj = new SuperHero(); 

if (obj is SuperHero) 

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

// Mark object for quick disposal

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

  string line;

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

    Console.WriteLine(line);

}

VB.NET

Structs

C#

Structure Student 

  Public name As String 

  Public gpa As Single 

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

    Me.name = name 

    Me.gpa = gpa 

  End Sub 

End Structure

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

Dim stu2 As Student = stu   

stu2.name = "Sue" 

Console.WriteLine(stu.name)    ' Prints Bob 

Console.WriteLine(stu2.name)  ' Prints Sue

struct Student {

  public string name;

  public float gpa;

  public Student(string name, float gpa) {

    this.name = name;

    this.gpa = gpa;

  }

}

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

Student stu2 = stu;  

stu2.name = "Sue";

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

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

VB.NET

Properties

C#

' Auto-implemented properties are new to VB10

Public Property Name As String

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

' Traditional property implementation

Private mName As String

Public Property Name() As String

    Get

        Return mName

    End Get

    Set(ByVal value As String)

        mName = value

    End Set

End Property

' Read-only property

Private mPowerLevel As Integer

Public ReadOnly Property PowerLevel() As Integer

    Get

        Return mPowerLevel

    End Get

End Property

' Write-only property

Private mHeight As Double

Public WriteOnly Property Height() As Double

    Set(ByVal value As Double)

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

    End Set

End Property

// Auto-implemented properties

public string Name { get; set; }

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

// Traditional property implementation

private string name;

public string Name {

  get {

    return name;

  }

  set {

    name = value;

  }

}

// Read-only property

private int powerLevel;

public int PowerLevel {

  get {

    return powerLevel;

  }

}

// Write-only property

private double height;

public double Height {

  set {

    height = value < 0 ? 0 : value;

  }

}

VB.NET

Generics

C#

' Enforce accepted data type at compile-time 

Dim numbers As New List(Of Integer)

numbers.Add(2)

numbers.Add(4)

DisplayList(Of Integer)(numbers)

' Subroutine can display any type of List 

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

    For Each item As T In list

        Console.WriteLine(item)

    Next

End Sub

' Class works on any data type 

Class SillyList(Of T)

    Private list(10) As T

    Private rand As New Random

    Public Sub Add(ByVal item As T)

        list(rand.Next(10)) = item

    End Sub

    Public Function GetItem() As T

        Return list(rand.Next(10))

    End Function

End Class

' Limit T to only types that implement IComparable

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

    Dim max As T = items(0)

    For Each item As T In items

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

    Next

    Return max

End Function

// Enforce accepted data type at compile-time 

List<int> numbers = new List<int>();

numbers.Add(2);

numbers.Add(4);

DisplayList<int>(numbers);

// Function can display any type of List 

void DisplayList<T>(List<T> list) {

    foreach (T item in list)

        Console.WriteLine(item);

}

// Class works on any data type 

class SillyList<T> {

    private T[] list = new T[10];

    private Random rand = new Random();

    public void Add(T item) {

        list[rand.Next(10)] = item;

    }

    public T GetItem() {

        return list[rand.Next(10)];

    }

}

// Limit T to only types that implement IComparable

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

    T max = items[0];

    foreach (T item in items)

        if (item.CompareTo(max) > 0)

            max = item;

    return max;

}

VB.NET

Delegates & Lambda Expressions

C#

Delegate Sub HelloDelegate(ByVal s As String)

Sub SayHello(ByVal s As String)

  Console.WriteLine("Hello, " & s)

End Sub

' Create delegate that calls SayHello

Dim hello As HelloDelegate = AddressOf SayHello

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

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

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

hello2("World")

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

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

Console.WriteLine(convert("test"))

Function Uppercase(s As String) As String

  Return s.ToUpper()

End Function

' Declare and invoke lambda expression

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

' Pass lambda expression as an argument

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

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

  If f(8, 4) Then

    Console.WriteLine("true")

  Else

    Console.WriteLine("false")

  End If

End Sub

delegate void HelloDelegate(string s);

void SayHello(string s) {

  Console.WriteLine("Hello, " + s);

}

// C# 1.0 delegate syntax with named method

HelloDelegate hello = new HelloDelegate(SayHello);

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

// C# 2.0 delegate syntax with anonymous method

HelloDelegate hello2 = delegate(string s) { 

  Console.WriteLine("Hello, " + s); 

};

hello2("World");

// C# 3.0 delegate syntax with lambda expression

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

hello3("World");

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

Func<string, string> convert = Uppercase;

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

string Uppercase(string s) {

  return s.ToUpper();

}

// Declare and invoke Func using a lambda expression

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

// Pass lamba expression as an argument

TestValues((x, y) => x % y == 0);

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

  if (f(8, 4))

    Console.WriteLine("true");

  else

    Console.WriteLine("false");

}

VB.NET

Events

C#

Delegate Sub MsgArrivedEventHandler(ByVal message As String)

Event MsgArrivedEvent As MsgArrivedEventHandler

' or to define an event which declares a delegate implicitly

Event MsgArrivedEvent(ByVal message As String)

AddHandler MsgArrivedEvent, AddressOf My_MsgArrivedCallback 

' Won't throw an exception if obj is Nothing

RaiseEvent MsgArrivedEvent("Test message") 

RemoveHandler MsgArrivedEvent, AddressOf My_MsgArrivedCallback

Imports System.Windows.Forms

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

MyButton = New Button

Sub MyButton_Click(ByVal sender As System.Object, _

  ByVal e As System.EventArgs) Handles MyButton.Click 

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

    MessageBoxButtons.OK, MessageBoxIcon.Information) 

End Sub

delegate void MsgArrivedEventHandler(string message);

event MsgArrivedEventHandler MsgArrivedEvent;

// Delegates must be used with events in C#

MsgArrivedEvent += new MsgArrivedEventHandler(My_MsgArrivedEventCallback);

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

MsgArrivedEvent -= new MsgArrivedEventHandler(My_MsgArrivedEventCallback);

using System.Windows.Forms;

Button MyButton = new Button(); 

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

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

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

    MessageBoxButtons.OK, MessageBoxIcon.Information); 

}

VB.NET

LINQ

C#

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

' Get all numbers in the array above 4

Dim results = From n In nums

                  Where n > 4

                  Select n

' Same thing using lamba expression

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

' Displays 5 8 6 

For Each n As Integer In results

    Console.Write(n & " ")

Next

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

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

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

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

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

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

results = results.Distinct()     ' 5 6 1 

Dim Students() As Student = {

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

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

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

} 

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

Dim goodStudents = From s In Students

            Where s.Gpa >= 3.0

            Order By s.Gpa Descending

            Select s

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

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

// Get all numbers in the array above 4

var results = from n in nums

                where n > 4

                select n;

// Same thing using lamba expression

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

// Displays 5 8 6 

foreach (int n in results)

    Console.Write(n + " ");

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

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

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

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

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

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

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

Student[] Students = {

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

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

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

};

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

var goodStudents = from s in Students

            where s.Gpa >= 3.0

            orderby s.Gpa descending

            select s;

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

VB.NET

Attributes

C#

' Attribute can be applied to anything

Public Class IsTestedAttribute

    Inherits Attribute

End Class

' Attribute can only be applied to classes or structs

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

Public Class AuthorAttribute

    Inherits Attribute

    Public Property Name As String

    Public Property Version As Integer = 0

    Public Sub New(ByVal name As String)

        Me.Name = name

    End Sub

End Class

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

Class Shape

    <IsTested()>

    Sub Move()

        ' Do something...

    End Sub

End Class

// Attribute can be applied to anything

public class IsTestedAttribute : Attribute

{

}

// Attribute can only be applied to classes or structs

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

public class AuthorAttribute : Attribute {

    public string Name { get; set; }

    public int Version { get; set; } 

    public AuthorAttribute(string name) {

        Name = name;

        Version = 0;

    }

}

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

class Shape {

    [IsTested]

    void Move() {

        // Do something...

    }

}

VB.NET

Console I/O

C#

Console.Write("What's your name? ") 

Dim name As String = Console.ReadLine() 

Console.Write("How old are you? ") 

Dim age As Integer = Val(Console.ReadLine()) 

Console.WriteLine("{0} is {1} years old.", name, age)  

' or 

Console.WriteLine(name & " is " & age & " years old.") 

Dim c As Integer 

c = Console.Read()    ' Read single char 

Console.WriteLine(c)   ' Prints 65 if user enters "A"

Console.Write("What's your name? ");

string name = Console.ReadLine();

Console.Write("How old are you? ");

int age = Convert.ToInt32(Console.ReadLine());

Console.WriteLine("{0} is {1} years old.", name, age);

// or

Console.WriteLine(name + " is " + age + " years old.");

int c = Console.Read();  // Read single char

Console.WriteLine(c);    // Prints 65 if user enters "A"

VB.NET

File I/O

C#

Imports System.IO

' Write out to text file

Dim writer As StreamWriter = File.CreateText("c:\myfile.txt") 

writer.WriteLine("Out to file.") 

writer.Close()

' Read all lines from text file

Dim reader As StreamReader = File.OpenText("c:\myfile.txt") 

Dim line As String = reader.ReadLine() 

While Not line Is Nothing 

  Console.WriteLine(line) 

  line = reader.ReadLine() 

End While 

reader.Close()

' Write out to binary file

Dim str As String = "Text data" 

Dim num As Integer = 123 

Dim binWriter As New BinaryWriter(File.OpenWrite("c:\myfile.dat"))  

binWriter.Write(str)  

binWriter.Write(num) 

binWriter.Close()

' Read from binary file

Dim binReader As New BinaryReader(File.OpenRead("c:\myfile.dat")) 

str = binReader.ReadString() 

num = binReader.ReadInt32() 

binReader.Close()

using System.IO;

// Write out to text file

StreamWriter writer = File.CreateText("c:\\myfile.txt"); 

writer.WriteLine("Out to file."); 

writer.Close();

// Read all lines from text file

StreamReader reader = File.OpenText("c:\\myfile.txt"); 

string line = reader.ReadLine(); 

while (line != null) {

  Console.WriteLine(line); 

  line = reader.ReadLine(); 

} 

reader.Close();

// Write out to binary file

string str = "Text data"; 

int num = 123; 

BinaryWriter binWriter = new BinaryWriter(File.OpenWrite("c:\\myfile.dat")); 

binWriter.Write(str); 

binWriter.Write(num); 

binWriter.Close();

// Read from binary file

BinaryReader binReader = new BinaryReader(File.OpenRead("c:\\myfile.dat")); 

str = binReader.ReadString(); 

num = binReader.ReadInt32(); 

binReader.Close();