VB.NET | C# |
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 | C# |
VB.NET
Comments
C#
' Single line only_
Rem Single line only_
// Single line_
/* Multiple
line */
/// XML comments on single line
/** XML comments on multiple lines */_
VB.NET | C# |
VB.NET
Data Types
C#
_Value Types_Boolean
Byte
Char _(example: "A"c)_Short, Integer, Long
Single, Double
Decimal
Date
_Reference Types_Object
String
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 _(example: 'A')_short, ushort, int, uint, long, ulong
float, double
decimal
DateTime (not a built-in C# type)
_Reference Types_object
string
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 to 3 (truncates decimal)
VB.NET | C# |
VB.NET
Constants
C#
Const MAX_STUDENTS As Integer = 25
' Can set to a const or var; may be initialized in a constructorReadOnly MIN_DIAMETER As Single = 4.93
const int MAX_STUDENTS = 25;
// Can set to a const or var; may be initialized in a constructorreadonly float MIN_DIAMETER = 4.93f;
VB.NET | C# |
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 | C# |
VB.NET
Operators
C#
Comparison= < > <= >= <>
Arithmetic+ - * /
Mod
\ (integer division)^ (raise to a power)
Assignment= += -= *= /= \= ^= <<= >>= &=
_Bitwise_And Or 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 | C# |
VB.NET
Choices
C#
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 lineIf x <> 100 And y < 5 Then x *= 5 : y *= 2
' PreferredIf 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 > Lines Then _
UseTheUnderscore(charToBreakItUp)
'If x > 5 Then
x *= y
ElseIf x = 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}
VB.NET | C# |
VB.NET
Loops
C#
Pre-test Loops: | |
While c < 10 | Do Until c = 10 |
Do While c < 10 | For c = 2 To 10 Step 2 |
| |
Do | Do |
_' 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:
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
Pre-test Loops:
// no "until" keywordwhile (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 < 5; i++) {
if (i < 4)
continue;
Console.WriteLine(i); // Only prints 4}
VB.NET | C# |
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
_// 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;
VB.NET | C# |
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("Madonna")
_// 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# doesn't support 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, "");
}
VB.NET | C# |
VB.NET
Strings
C#
_Special character constants_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
Console.WriteLine(mascot.Substring(2, 3)) ' Prints "son"
_' String matching_If ("John 3:16" Like "Jo[Hh]? #:*") Then 'true
Imports System.Text.RegularExpressions _' More powerful than Like_Dim r As New Regex("Jo[hH]. \d:*")
If (r.Match("John 3:16").Success) Then 'true
_' My birthday: Oct 12, 1973_Dim dt As New DateTime(1973, 10, 12)
Dim s As String = "My birthday: " & dt.ToString("MMM dd, yyyy")
_' 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\n, \r
\t
\\
\"
// String concatenationstring school = "Harding\t";
school = school + "University"; // school is "Harding (tab) University"
// Charschar letter = school[0]; // letter is H
letter = Convert.ToChar(65); // letter is A
letter = (char)65; // same thingchar[] 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_string mascot = "Bisons";
if (mascot == "Bisons") _// true_if (mascot.Equals("Bisons")) _// true_if (mascot.ToUpper().Equals("BISONS")) _// true_if (mascot.CompareTo("Bisons") == 0) // true
Console.WriteLine(mascot.Substring(2, 3)); // Prints "son"
// String matching_
// No Like equivalent - use regular expressions_
using System.Text.RegularExpressions;
Regex r = new Regex(@"Jo[hH]. \d:*");
if (r.Match("John 3:16").Success) // true
_// My birthday: Oct 12, 1973_DateTime dt = new DateTime(1973, 10, 12);
string s = "My birthday: " + dt.ToString("MMM dd, yyyy");
// 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 | C# |
VB.NET
Exception Handling
C#
_' Throw an exception_Dim ex As New Exception("Something is really wrong.")
Throw ex
' Catch an exceptionTry 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 handlingOn 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 exceptiontry {
y = 0;
x = 10 / y;
}
catch (Exception ex) { // Argument is optional, no "When" keyword
Console.WriteLine(ex.Message);
}
finally {
// Requires reference to the Microsoft.VisualBasic.dll // assembly (pre .NET Framework v2.0)
Microsoft.VisualBasic.Interaction.Beep();
}
VB.NET | C# |
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 | C# |
VB.NET
Classes / Interfaces
C#
Accessibility keywords
Public
Private
Friend
Protected
Protected Friend
Shared
' InheritanceClass FootballGame
Inherits Competition
...
End Class
' Interface definitionInterface IAlarmClock
...
End Interface
// Extending an interface Interface IAlarmClock
Inherits IClock
...
End Interface
// Interface implementationClass WristWatch
Implements IAlarmClock, ITimer
...
End Class
Accessibility keywords
public
private
internal
protected
protected internal
static
// Inheritanceclass FootballGame : Competition {
...
}
// Interface definition
interface IAlarmClock {
...
}
// Extending an interface interface IAlarmClock : IClock {
...
}
// Interface implementation
class WristWatch : IAlarmClock, ITimer {
...
}
VB.NET | C# |
VB.NET
Constructors / Destructors
C#
Class SuperHero
Private _powerLevel As Integer
Public Sub New()
_powerLevel = 0
End Sub
Public Sub New(ByVal powerLevel As Integer)
Me._powerLevel = powerLevel
End Sub
Protected Overrides Sub Finalize()
' Desctructor code to free unmanaged resources
MyBase.Finalize()
End Sub
End Class
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 }
}
VB.NET | C# |
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 disposalUsing 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.");
// Mark object for quick disposalusing (StreamReader reader = File.OpenText("test.txt")) {
string line;
while ((line = reader.ReadLine()) != null)
Console.WriteLine(line);
}
VB.NET | C# |
VB.NET
Structs
C#
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
struct StudentRecord {
public string name;
public float gpa;
public StudentRecord(string name, float gpa) {
this.name = name;
this.gpa = gpa;
}
}
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
VB.NET | C# |
VB.NET
Properties
C#
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
private int _size;
public int Size {
get {
return _size;
}
set {
if (value < 0)
_size = 0;
else
_size = value;
}
}
foo.Size++;
VB.NET | C# |
VB.NET
Delegates / Events
C#
Delegate Sub MsgArrivedEventHandler(ByVal message As String)
Event MsgArrivedEvent As MsgArrivedEventHandler
' or to define an event which declares a delegate implicitlyEvent MsgArrivedEvent(ByVal message As String)
AddHandler MsgArrivedEvent, AddressOf My_MsgArrivedCallback
' Won't throw an exception if obj is NothingRaiseEvent 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, "Button was clicked", "Info",
MessageBoxButtons.OK, MessageBoxIcon.Information);
}
VB.NET | C# |
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 | C# |
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 fileStreamWriter writer = File.CreateText("c:\\myfile.txt");
writer.WriteLine("Out to file.");
writer.Close();
// Read all lines from text fileStreamReader 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 fileBinaryReader binReader = new BinaryReader(File.OpenRead("c:\\myfile.dat"));
str = binReader.ReadString();
num = binReader.ReadInt32();
binReader.Close();