So sánh sự khác nhau giữa VB.Net và C#

[code language=”vbnet”] Imports System

Namespace MinhHoangBlog
Class HelloWorld
‘ Cách truyền tham số cho hàm
Overloads Shared Sub Main(ByVal args() As String)
‘ Cách khai báo biến và khởi tạo giá trị
Dim name As String = "VB.NET"

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

‘ Cách nối chuỗi
Console.WriteLine( "Hello, " & name & "!" )
End Sub
End Class
End Namespace
[/code]

[code language=”csharp”] using System;

namespace MinhHoangBlog
{
public class HelloWorld
{
// Cách truyền tham số cho hàm
public static void Main(string[] args)
{
// Cách khai báo biến và khởi tạo giá trị
string name = "C#";

if (args.Length == 1) name = args[0];

// Cách nối chuỗi
Console.WriteLine( "Hello, " + name + "!" );
}
}
}
[/code]

[code language=”vbnet”] ‘ Chỉ có comment 1 dòng

‘ KHÔNG có comment nhiều dòng

”’ <summary>Mô tả ý nghĩa của hàm hoặc class,…</summary>
[/code]

[code language=”csharp”] // Comment một dòng

/* Comment
nhiều dòng */

/* Comment
* nhiều dòng
*/

/// <summary>Mô tả ý nghĩa của hàm hoặc class,… một dòng</summary>
/** <summary>Mô tả ý nghĩa của hàm hoặc class,… nhiều dòng</summary> */
[/code]

[code language=”vbnet”] Namespace WelcomeTo.MinhHoang.Blog
‘ bla bla
End Namespace

‘ or

Namespace WelcomeTo
Namespace MinhHoang
Namespace Blog
‘ bla bla
End Namespace
End Namespace
End Namespace

Imports WelcomeTo.MinhHoang.Blog
[/code]

[code language=”csharp”] namespace WelcomeTo.MinhHoang.Blog
{
// bla bla
}

// or

namespace WelcomeTo
{
namespace MinhHoang
{
namespace Blog
{
// bla bla
}
}
}

using WelcomeTo.MinhHoang.Blog;
[/code]

[code language=”vbnet”] Class SuperHero
Inherits Person ‘ Cách thể hiện thừa kế

Private powerLevel As Integer
Private name As String

‘ Constructor mặc định
Public Sub New()
powerLevel = 0
name = "Robin Hood"
End Sub

Public Sub New(ByVal powerLevel As Integer)
Me.New( "Robin Hood" ) ‘ Gọi constructor của chính nó
Me.powerLevel = powerLevel
End Sub

Public Sub New(ByVal name As String)
MyBase.New(name) ‘ Gọi constructor của base class
Me.name = name
End Sub

Shared Sub New()
‘ Shared constructor được gọi trước khi instance đầu tiên được tạo
End Sub

Protected Overrides Sub Finalize()
‘ Destructor Giải phóng tài nguyên không dùng sau khi kết thúc chương trình
MyBase.Finalize()
End Sub
End Class
[/code]

[code language=”csharp”] class SuperHero : Person // Cách thể hiện thừa kế
{
private int powerLevel;
private string name;

// Constructor mặc định
public SuperHero()
{
powerLevel = 0;
name = "Robin Hood";
}

// Gọi constructor của chính nó
public SuperHero(int powerLevel) : this( "Robin Hood" )
{
this.powerLevel = powerLevel;
}

// Gọi constructor của base class
public SuperHero(string name) : base(name)
{
this.name = name;
}

static SuperHero()
{
// Static constructor được gọi trước khi instance đầu tiên được tạo
}

~SuperHero()
{
// Destructor ngầm định tạo ra phương thức Finalize() để giải phóng tài nguyên bộ nhớ
// trước khi thoát khỏi chương trình
}
}
[/code]

[code language=”vbnet”] ‘ Input giá trị nhập vào từ bàn phím
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())

‘ Output thông tin ra console
Console.WriteLine("{0} is {1} years old.", name, age)
‘ or
Console.WriteLine( name & " is " & age & " years old." )

Dim c As Integer = Console.Read()
Console.WriteLine(c) ‘ Nếu nhập A thì sẽ hiện ra ở console là 65
[/code]

[code language=”csharp”] /*　Input giá trị nhập vào từ bàn phím */
Console.Write( "What’s your name? " );
string name = Console.ReadLine();

Console.Write( "How old are you? " );
int age = Convert.ToInt32(Console.ReadLine());

/*　Output thông tin ra console */
Console.WriteLine("{0} is {1} years old.", name, age);
// or
Console.WriteLine( name + " is " + age + " years old." );

int c = Console.Read();
Console.WriteLine(c); // Nếu nhập A thì sẽ hiện ra ở console là 65
[/code]

[code language=”vbnet”] ‘ 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
&
[/code]

[code language=”csharp”] // 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
+
[/code]

[code language=”vbnet”] ‘ Value Types
Boolean
Byte, SByte
Char
Short, UShort, Integer, UInteger, Long, ULong
Single, Double
Decimal
Date ‘ (alias of System.DateTime)
structures
enumerations

‘ Reference Types
objects
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()) ‘ System.Int32
Console.WriteLine(GetType(Integer)) ‘ System.Int32
Console.WriteLine(TypeName(x)) ‘ 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
[/code]

[code language=”csharp”] // 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
objects
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()); // System.Int32
Console.WriteLine(typeof(int)); // System.Int32
Console.WriteLine(x.GetType().Name); // 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
[/code]

[code language=”vbnet”] 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
[/code]

[code language=”csharp”] const int MAX_STUDENTS = 25;

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

[code language=”vbnet”] ‘ 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)) ‘ son
s = Mid("testing", 2, 3) ‘ est

‘ 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"
[/code]

[code language=”csharp”] // 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)) // son
s = "testing".Substring(1, 3); // est (no Mid)

// Replacement
s = mascot.Replace( "sons", "nomial" )) // 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"
[/code]

[code language=”vbnet”] 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
[/code]

[code language=”csharp”] 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;
[/code]

[code language=”vbnet”] 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) ‘ "Stop is 1"

Console.WriteLine(Status.Pass) ‘ 70
Console.WriteLine(Status.Pass.ToString) ‘ Pass
[/code]

[code language=”csharp”] 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); // "Stop is 1"

Console.WriteLine((int) Status.Pass); // 70
Console.WriteLine(Status.Pass); // Pass
[/code]

[code language=”vbnet”] Structure Student
Public name As String
Public age As Integer

Public Sub New(ByVal name As String, ByVal age As Integer)
Me.name = name
Me.age = age
End Sub
End Structure

Dim std1 As Student = New Student("Peter", 20)
Dim std2 As Student = std1

stu2.name = "Marry"
Console.WriteLine(std1.name) ‘ Output: Peter
Console.WriteLine(std2.name) ‘ Output: Marry
[/code]

[code language=”csharp”] struct Student
{
public string name;
public int age;

public Student(string name, int age)
{
this.name = name;
this.age = age;
}
}
Student std1 = new Student("Peter", 20);
Student std2 = std1;

std2.name = "Marry";
Console.WriteLine(std1.name); // Output: Peter
Console.WriteLine(std2.name); // Output: Marry
[/code]

[code language=”vbnet”] 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
[/code]

[code language=”csharp”] 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);
}
[/code]

[code language=”vbnet”] ‘ 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
[/code]

[code language=”csharp”] // 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
}
[/code]

[code language=”vbnet”] ‘ 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
[/code]

[code language=”csharp”] // 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
}
[/code]

[code language=”vbnet”] ‘ 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" )
[/code]

[code language=”csharp”] // 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" );
[/code]

[code language=”vbnet”] 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
[/code]

[code language=”csharp”] 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
[/code]

[code language=”vbnet”] ‘ 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)
[/code]

[code language=”csharp”] // Throw an exception
Exception up = new Exception( "Something is really wrong." );
throw up;

// 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();
}
[/code]

[code language=”vbnet”] ‘ 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 Team
…
Protected name As String
Public Overridable Sub DisplayName()
Console.WriteLine(name)
End Sub
End Class

‘ Inheritance
Class FootballTeam
Inherits Team
…
Public Overrides Sub DisplayName()
Console.WriteLine( "** " + name + " **" )
End Sub
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
[/code]

[code language=”csharp”] // 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 Team
{
…
protected string name;
public virtual void DislpayName()
{
Console.WriteLine(name);
}

// Inheritance
class FootballTeam : Team
{
…
public override void DislpayName()
{
Console.WriteLine( "** " + name + " **" );
}
}

// 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; }
…
}
[/code]

[code language=”vbnet”] ‘ 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
[/code]

[code language=”csharp”] // 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;
}
}
[/code]

[code language=”vbnet”] ‘ 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
[/code]

[code language=”csharp”] // 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;
}
[/code]

[code language=”vbnet”] ‘ Popular classes In System.Collections (stored As Object)
ArrayList
Hashtable
Queue
Stack

‘ Popular classes In System.Collections.Generic (stored As type T)
List(Of T)
SortedList(Of TKey, TValue)
Dictionary(Of TKey, TValue)
Queue(Of T)
Stack(Of T)

‘ Popular classes In System.Collections.Concurrent (thread safe)
BlockingCollection(Of T)
ConcurrentDictionary(Of TKey, TValue)
ConcurrentQueue(Of T)
ConcurrentStack(Of T)

‘ Microsoft.VisualBasic(Not recommended)
Collection

‘ Store ID and name
Dim students As New Dictionary(Of Integer, String) From
{
{123, "Bob"},
{444, "Sue"},
{555, "Jane"}
}

students.Add( 987, "Gary" )
Console.WriteLine(students(444)) ‘ Sue

‘ Display all
For Each stu In students
Console.WriteLine(stu.Key & " = " & stu.Value)
Next

‘ Method iterator for custom iteration over a collection
Iterator Function OddNumbers(ByVal lastNum As Integer) As System.Collections.IEnumerable
For num = 1 To lastNum
If num Mod 2 = 1 Then
Yield num
End If
Next
End Function

‘ 1 3 5 7
For Each num In OddNumbers(7)
Console.Write( num & " " )
Next
[/code]

[code language=”csharp”] // Popular classes in System.Collections (stored as Object)
ArrayList
Hashtable
Queue
Stack

// Popular classes in System.Collections.Generic (stored as type T)
List<T>
SortedList<TKey, TValue>
Dictionary<TKey, TValue>
Queue<T>
Stack<T>

// Popular classes in System.Collections.Concurrent (thread safe)
BlockingCollection<T>
ConcurrentDictionary<TKey, TValue>
ConcurrentQueue<T>
ConcurrentStack<T>

// No equivalent to Microsoft.VisualBasic.Collection

// Store ID and name
var students = new Dictionary<int, string>
{
{ 123, "Bob" },
{ 444, "Sue" },
{ 555, "Jane" }
};

students.Add( 987, "Gary" );
Console.WriteLine(students[444]); // Output: Sue

// Display all
foreach (var stu in students) {
Console.WriteLine(stu.Key + " = " + stu.Value);
}

// Method iterator for custom iteration over a collection
static System.Collections.Generic.IEnumerable<int> OddNumbers(int lastNum)
{
for (var num = 1; num <= lastNum; num++)
if (num % 2 == 1)
yield return num;
}

// 1 3 5 7
foreach (double num in OddNumbers(7))
{
Console.Write( num + " " );
}
[/code]

[code language=”vbnet”] ‘ Khai báo
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
[/code]

[code language=”csharp”] // Khai báo
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" );
}
[/code]

[code language=”vbnet”] Imports System.Runtime.CompilerServices

Module StringExtensions
<Extension()>
Public Function VowelCount(ByVal s As String) As Integer
Return s.Count(Function(c) "aeiou".Contains(Char.ToLower(c)))
End Function
End Module

‘ Using the extension method
Console.WriteLine("This is a test".VowelCount)
[/code]

[code language=”csharp”] public static class StringExtensions
{
public static int VowelCount(this string s)
{
return s.Count(c => "aeiou".Contains(Char.ToLower(c)));
}
}

// Using the extension method
Console.WriteLine("This is a test".VowelCount());
[/code]

[code language=”vbnet”] 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
[/code]

[code language=”csharp”] 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);
}
[/code]

[code language=”vbnet”] 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
[/code]

[code language=”csharp”] 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
[/code]

[code language=”vbnet”] ‘ 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
[/code]

[code language=”csharp”] // 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…
}
}
[/code]

[code language=”vbnet”] 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()
[/code]

[code language=”csharp”] 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();
[/code]