// Single line
/* Multiple
line */
/// <summary>XML comments on single line</summary>
/** <summary>XML comments on multiple lines</summary> */

Value Types
Boolean
Byte,SByte
Char
Short,UShort,Integer,UInteger,Long,ULong
Single,Double
Decimal
Date

Reference Types
Object
String

Initializing
Dim correct As Boolean = True
Dim b As Byte = &H2A 'hex
Dim o As Byte = &O52 'octal
Dim person As Object = Nothing
Dim name As String = "Dwight"
Dim grade As Char = "B"c
Dim today As Date = #12/31/2007 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

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

Type Conversion
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)

Value Types
bool
byte,sbyte
char
short,ushort,int,uint,long,ulong
float,double
decimal
DateTime (not a built-in C#type)

Reference Types
object
string

Initializing
bool correct = true;
byte b = 0x2A; // hex

object person = null;
string name = "Dwight";
char grade = 'B';
DateTime today = DateTime.Parse("12/31/2007 12:15:00");
decimal amount = 35.99m;
float gpa = 2.9f;
double pi = 3.14159265;
long lTotal = 123456L;
short sTotal = 123;
ushort usTotal = 123;
uint uiTotal = 123;
ulong ulTotal = 123;

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

Type Conversion
float d = 3.5f;
int i = (int)d; // set to3 (truncates decimal)

' Can set to a const orvar; may be initialized in a constructor
ReadOnly MIN_DIAMETER As Single = 4.93

// Can set to a const or var; may be initialized in a constructor
readonly float MIN_DIAMETER = 4.93f;

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
+

greeting = IIf(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 And y < 5 Then x *= 5 : y *= 2

' Preferred
If x <> 100 And y < 5 Then
x *= 5
y *= 2
End If

' To break up any long single line use _
If whenYouHaveAReally < longLine And _
itNeedsToBeBrokenInto2> LinesThen _
UseTheUnderscore(charToBreakItUp)

'If x > 5 Then
x *= y
ElseIfx = 5 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

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)
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
}

' Array or collection looping
Dim names As String() = {"Fred","Sue","Barney"}
For Each s As StringIn 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

// 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","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 < 5; i++) {
if (i < 4)
continue;
Console.WriteLine(i); // Only prints 4
}

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 = {1,3};
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


// C# can't dynamically resize an array. Just copy into new array.
string[] names2 = new string[7];
Array.Copy(names,names2,names.Length); // or names.CopyTo(names2,0);

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;

' Pass by value (in,default),reference (in/out),andreference (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 ' cset to zero by default
TestFunc(a,b,c)
Console.WriteLine("{0} {1} {2}",a,c) ' 12 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(4,3,1) ' returns 10

' Optional parameters must belisted lastand 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("Madonna")

int a = 1,c; // c doesn't need initializing
TestFunc(a,ref b,out c);
Console.WriteLine("{0} {1} {2}",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(4,1); // returns 10

/* C# doesn'tsupport optional arguments/parameters. Just create two different versions of the same function. */
void SayHello(string name,string prefix) {
Console.WriteLine("Greetings," + prefix + " " + name);
}

void SayHello(string name) {
SayHello(name,"");
}

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"

' Chars
Dim letter As Char = school.Chars(0) ' letter is H
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 msg As String = "File is 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 = "Frank,Becky,Ethan,Braden"
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"

// Chars
char letter = school[0]; // letter is H
letter = Convert.tochar(65); // letter is A
letter = (char)65; // same thing
char[] word = school.tocharArray(); // word holds Harding

// String literal
string msg = @"File is c:/temp/x.dat";
// same as
string msg = "File is c://temp//x.dat";

// String comparison
stringmascot = "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 = "Frank,Braden";
string[] parts = names.Split(",".tocharArray()); // One name in each slot

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

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

// 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"

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 = "Frank,Braden"
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 = "Frank,Braden";
Regex r = new Regex(@",/s*");
string[] parts = r.Split(names); // One name in each slot

' 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 ExceptionWhen 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();
}

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;

Accessibility keywords
Public
Private
Friend
Protected
Protected Friend
Shared

' Inheritance
ClassFootballGame
InheritsCompetition
...
End Class

' Interface definition
Interface IAlarmClock
...
End Interface

// Extending an interface
Interface IAlarmClock
Inherits IClock
...
End Interface

// Interface implementation
Class WristWatch
Implements IAlarmClock,ITimer
...
End Class

Accessibility keywords
public
private
internal
protected
protected internal
static

// Inheritance
classFootballGame : Competition {
...
}

// Interface definition
interface IAlarmClock {
...
}

// Extending an interface
interface IAlarmClock : IClock {
...
}

// Interface implementation
class WristWatch : IAlarmClock,ITimer {
...
}

class SuperHero {
private int _powerLevel;

public SuperHero() {
_powerLevel = 0;
}

public SuperHero(int powerLevel) {
this._powerLevel= powerLevel;
}

~SuperHero() {
// Destructor code to free unmanaged resources.
// Implicitly creates a Finalize method
}
}

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" construct
hero.Name = "SpamMan";
hero.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.");

Structure StudentRecord
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 StudentRecord = New StudentRecord("Bob",3.5)
Dim stu2 As StudentRecord = stu

stu2.name = "Sue"
Console.WriteLine(stu.name) ' Prints Bob
Console.WriteLine(stu2.name) ' Prints Sue

StudentRecord stu = new StudentRecord("Bob",3.5f);
StudentRecord stu2 = stu;

stu2.name = "Sue";
Console.WriteLine(stu.name); // Prints Bob
Console.WriteLine(stu2.name); // Prints Sue

Private _size As Integer

Public Property Size() As Integer
Get
Return _size
End Get
Set (ByVal Value As Integer)
If Value < 0 Then
_size = 0
Else
_size = Value
End If
End Set
End Property

foo.Size += 1

foo.Size++;

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

Private 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);

private void MyButton_Click(object sender,System.EventArgs e) {
MessageBox.Show(this,
MessageBoxButtons.OK,MessageBoxIcon.Information);
}

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.",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"

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();