C#

More relaxing jobs are more dangerous: Economic Slowdown, JOB CUTs and Software Developer.

Mahesh Singh — Wed, 15 Oct 2008 19:36:45 GMT

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More relaxing jobs are more dangerous: Economic Slowdown, JOB CUTs and Software Developer

VB.NET and C# Syntax Comparison

Mahesh Singh — Fri, 04 Jan 2008 00:51:14 GMT

VB.NET and C# Syntax Comparison

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Imports System

Namespace HelloNamespace
   Class HelloClass
      Overloads Shared Sub Main(ByVal args() As String)
         Dim name As String = "VB.NET"

         '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 HelloNamespace {
   public class HelloClass{
      public static void Main(string[] args) {
         string name = "C#";

         // If an argument was passed from the command line
         if (args.Length == 1)
            name = args[0];

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

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' 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> */

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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 to 3 (truncates decimal)

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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;

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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

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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
+

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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 > 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
}

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

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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;

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' Pass by value (in, default), reference (in/out), and reference (out)
Sub TestFunction(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
TestFunction(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 TestFunction(int x, ref int y, out int z) {
x++;
y++;
z = 5;
}

int a = 1, b = 1, c; // c doesn't need initializing
TestFunction(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, "");
}

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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
\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
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"

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' 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 {
// Requires reference to the Microsoft.VisualBasic.dll
// assembly (pre .NET Framework v2.0)
Microsoft.VisualBasic.Interaction.Beep();
}

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Namespace MyCompany.Product
...
End Namespace

' or

Namespace MyCompany
Namespace Product

      ...

End Namespace
End Namespace

Imports MyCompany.Product

namespace MyCompany.Product {
...
}

// or

namespace MyCompany{
namespace Product {

      ...

}
}

using MyCompany.Product;

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Accessibility keywords
Public
Private
Friend
Protected
Protected Friend
Shared

' Inheritance
Class Game
Inherits Competition
...
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
class Game : Competition {
...
}

// Interface definition
interface IAlarmClock {
...
}

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

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

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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
}
}

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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.");

// Mark object for quick disposal
using (StreamReader reader = File.OpenText("test.txt")) {
string line;
while ((line = reader.ReadLine()) != null)
Console.WriteLine(line);
}

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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

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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++;

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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, "Button was clicked", "Info",
MessageBoxButtons.OK, MessageBoxIcon.Information);
}

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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"

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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();

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Source: http://www.harding.edu/fmccown/vbnet_csharp_comparison.html

Items collection cannot be modified when the DataSource property is set.

Mahesh Singh — Thu, 27 Dec 2007 01:59:37 GMT

Items collection cannot be modified when the DataSource property is set.

This exception

“Items collection cannot be modified when the DataSource property is set.”

occurs when you trying to add some text like “Select” or “None” in combo box (drop down list) in .NET framework window form control. There is no such way to add items in combo box’s items property after you set DataSource. To avoid this you can add one more item in your datasource. For example if you are trying to bind drop down list through DataSet then add one more row into DataSet. There is one more workaround for

“Items collection cannot be modified when the DataSource property is set.”

If you like? http://www.codeproject.com/KB/combobox/UnboundItemsComboBox.aspx Hope this will help you to solve the exception

“Items collection cannot be modified when the DataSource property is set.”

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ASP.NET Web Services Interview Questions

Mahesh Singh — Tue, 25 Dec 2007 09:19:35 GMT

ASP.NET Web Services Interview Questions

Which page is used to display the link of webmethods in ASP.NET web services?

If your webmethod is having return type is void and while consuming the webservices you don’t want to wait the complete execution to that method. How would you achive this?

How you would make your web services to participate in transaction?

What would be key requirement to make ASP.NET web application an ASP.NET Web Services?

What is the primary purpose of Namespace property, which is used in WebServices attribute?

Identify invalid WebServices declaration?

While creating Web Service through visual studio template, which namespaces are include automatically?

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ASP.NET Web Services Interview Questions

Mahesh Singh — Tue, 25 Dec 2007 09:18:54 GMT

ASP.NET Web Services Interview Questions

Which method is used to serialize an object into an XML document from Xmlserializer class?

How to specify the Web Service compile with the WS-I basic profile?

For SOAP (Simple Object Access Protocol) message formatting what is the purpose of Encoded value?

What are the three main section of SOAP (Simple Object Access Protocol) message?

What all steps are required to create an application to test your ASP.NET web services?

How you can verify the result of your ASP.NET web services?

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ASP.NET Web Services Interview Questions

Mahesh Singh — Tue, 25 Dec 2007 09:18:16 GMT

ASP.NET Web Services Interview Questions

How do you configure the SOAP (Simple Object Access Protocol) to associate with particular web method?

Which method of SoapExtension class is used to intercept the incoming stream and determine the stage?

Which is a true statement for BeforeSerialize stage of an in-coming request message occurs?

What value can be used when setting the direction of the SOAP header?

Which is not the step to create custom SOAP (Simple Object Access Protocol) header class?

What kind of information included in SOAP (Simple Object Access Protocol) header?

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ASP.NET Web Services Quiz

Mahesh Singh — Tue, 25 Dec 2007 09:11:39 GMT

ASP.NET Web Services Quiz

Thanks
~Mahesh

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Lazy Loading

Mahesh Singh — Thu, 26 Oct 2006 14:42:00 GMT

Not to load code modules into memory until you are sure you are going to be required. Example:

I am having Category and Sub-Category. Category can hold list of Sub-Category, but this sub-category is not require every time. I’ll load sub-category when it is required. I am using following code to achieve this.

public class Category

{

// Other Geter Seter..

private List<SubCategory> _subCategories;

/// <summary>

/// Sub Categories

/// </summary>

public List<SubCategory> SubCategories

{

get

{

//Lazy Load

if (_subCategories == null)

_subCategories = GetSubCategories(this.ID);

return _subCategories;

}

set { _subCategories = value; }

}

I’ll not fill list of sub-category in default load of Category object (cunstructor or some Load method) instant of I’ll load list of sub-category when it is acthuly required.

http://www.martinfowler.com/eaaCatalog/lazyLoad.html

Brief about Static modifier in C#

Mahesh Singh — Wed, 27 Sep 2006 15:46:00 GMT

Static modifier used with the class, field, method, properties, operator, event and constructors. We can not use static modifier with indexers, destructors.

When we use static modifier with the members then they are no more part of instance of a class. Static members are a part of class itself.

For example:

public class MyClass

{

public struct MyStruct

{

public static int x = 100;

}

//To refer to the static member x, use the fully qualified name

MyClass.MyStruct.x

Consider a class that represents a student. Assume that the class contains a method to count student. Both the method does not belong to any instance student. Instead they belong to the College class. Therefore, they should be declared as static members of the college class.

Static Class

If static modifier is apply to the class then all member of class must be static.

Classes, including static classes, may have static constructors.

It is not possible to make an instance of static class with “new” keyword.

Features of static class:

1. They can only contain static members.

2. They are sealed means we cannot inherit the class.

3. They can not contain non static constructors

Static Members and Constructor:

Static members are initialized before the static member is accessed for the first time.

A static constructor is used to initialize any static data, or to perform a particular action that needs performed once only. It is called automatically before the first instance is created or any static members are referenced.

A static constructor does not take access modifiers or have parameters.

A typical use of static constructors is when the class is using a log file and the constructor is used to write entries to this file.

Cheers!

Mahesh

maheshsingh21@hotmail.com

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Abstract Class vs Interface

Mahesh Singh — Wed, 05 Jul 2006 15:38:00 GMT

Introduction:

There are lost of discussion on the internet about the Interface vs Abstract class. Also, as base class whether we have to use interface, abstract class or normal class.

I am trying to point out few considerations on which we can take decision about Interface vs Abstract class vs Class.

Abstract Class vs Interface

I am assuming you are having all the basic knowledge of abstract and interface keyword. I am just briefing the basics.

We can not make instance of Abstract Class as well as Interface.

Here are few differences in Abstract class and Interface as per the definition.

Abstract class can contain abstract methods, abstract property as well as other members (just like normal class).

Interface can only contain abstract methods, properties but we don’t need to put abstract and public keyword. All the methods and properties defined in Interface are by default public and abstract.

//Abstarct Class

public abstract class Vehicles

{

private int noOfWheel;

private string color;

public abstract string Engine

{

get;

set;

}

public abstract void Accelerator();

}

//Interface

public interface Vehicles

{

string Engine

{

get;

set;

}

void Accelerator();

}

We can see abstract class contains private members also we can put some methods with implementation also. But in case of interface only methods and properties allowed.

We use abstract class and Interface for the base class in our application.

This is all about the language defination. Now million doller question:

How can we take decision about when we have to use Interface and when Abstract Class.

Basicly abstact class is a abstract view of any realword entity and interface is more abstract one. When we thinking about the entity there are two things one is intention and one is implemntation. Intention means I know about the entity and also may have idea about its state as well as behaviour but don’t know about how its looks or works or may know partially. Implementation means actual state and behaviour of entity.

Enough theory lets take an example.

I am trying to make a Content Management System where content is a genralize form of article, reviews, blogs etc.

CONTENT

ARTICLE

BLOGS

REVIEW

So content is our base class now how we make a decision whether content class should be Abstract class, Interface or normal class.

First normal class vs other type (abstract and interface). If content is not a core entity of my application means as per the business logic if content is nothing in my application only Article, Blogs, Review are the core part of business logic then content class should not be a normal class because I’ll never make instance of that class. So if you will never make instance of base class then Abstract class and Interface are the more appropriate choice.

Second between Interface and Abstract Class.

CONTENT

Publish ()

ARTICLE

BLOGS

REVIEW

As you can see content having behavior named “Publish”. If according to my business logic Publish having some default behavior which apply to all I’ll prefer content class as an Abstract class. If there is no default behavior for the “Publish” and every drive class makes their own implementation then there is no need to implement “Publish” behavior in the base case I’ll prefer Interface.

These are the in general idea of taking decision between abstract class, interface and normal class. But there is one catch. As we all know there is one constant in software that is “CHANGE”. If I made content class as Interface then it is difficult to make changes in base class because if I add new method or property in content interface then I have to implement new method in every drive class. These problems will over come if you are using abstract class for content class and new method is not an abstract type. So we can replace interface with abstract class except multiple inheritance.

CAN-DO and IS-A relationship is also define the deference between Interface and abstract class. As we already discuss Interface can be use for multiple inheritance for example we have another interface named “ICopy” which having behavior copy and every drive class have to implements its own implementation of Copy. If “Article” class drive from abstract class Content as well as ICopy then article “CAN-DO” copy also.

IS-A is for “generalization” and “specialization” means content is a generalize form of Article, Blogs, Review and Article, Blogs, Review are a specialize form of Content.

So, abstract class defines core identity. If we are thinking in term of speed then abstract is fast then interface because interface requires extra in-direction.

So as per my view Abstract class having upper-hand in compare to interface. Using interface having only advantage of multiple inheritance. If you don’t understand the things then don’t worry because it’s my mistake because I am not able to describe the topic.

Code Complete 2

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C#

More relaxing jobs are more dangerous: Economic Slowdown, JOB CUTs and Software Developer.

VB.NET and C# Syntax Comparison

VB.NET and C# Syntax Comparison

Program Structure

Comments

Data Types

Constants

Enumerations

Operators

Choices

Loops

Arrays

Functions

Strings

Exception Handling

Namespaces

Classes / Interfaces

Constructors / Destructors

Using Objects

Structs

Properties

Delegates / Events

Console I/O

File I/O

Items collection cannot be modified when the DataSource property is set.

Items collection cannot be modified when the DataSource property is set.

“Items collection cannot be modified when the DataSource property is set.”

“Items collection cannot be modified when the DataSource property is set.”

“Items collection cannot be modified when the DataSource property is set.”

ASP.NET Web Services Interview Questions

ASP.NET Web Services Interview Questions

ASP.NET Web Services Interview Questions

ASP.NET Web Services Interview Questions

ASP.NET Web Services Interview Questions

ASP.NET Web Services Interview Questions

ASP.NET Web Services Quiz

ASP.NET Web Services Quiz

Lazy Loading

Brief about Static modifier in C#

Abstract Class vs Interface

Code Complete 2

A Leader Should Know How to Manage Failure