function در vb.net
برنامه بنویسید که عدد n را از ورودی گرفته و سری زیر را به کمک function محاسبه کند s=1/1!+1/2!+...+1/n!-----------none
در بالا قسمت آبی فرمول است. قسمت سیاه برای جلوگیری از جابجا شدن اضافه شده.
VB.NET Program Structure C#
Imports System
Namespace Hello
Class HelloWorld
Overloads Shared Sub Main(ByVal args() As String)
Dim name As String = "VB.NET"
'See if an argument was passed from the command line
If args.Length = 1 Then name = args(0)
Console.WriteLine("Hello, " & name & "!")
End Sub
End Class
End Namespace using System;
namespace Hello {
public class HelloWorld {
public static void Main(string[] args) {
string name = "C#";
// See if an argument was passed from the command line
if (args.Length == 1)
name = args[0];
Console.WriteLine("Hello, " + name + "!");
}
}
}
VB.NET Comments C#
' Single line only
REM Single line only
''' <summary>XML comments</summary>
// Single line
/* Multiple
line */
/// <summary>XML comments on single line</summary>
/** <summary>XML comments on multiple lines</summary> */
VB.NET Data Types C#
Value Types
Boolean
Byte, SByte
Char
Short, UShort, Integer, UInteger, Long, ULong
Single, Double
Decimal
Date (alias of System.DateTime)
Reference Types
Object
String
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
Implicitly Typed Local Variables
Dim s = "Hello!"
Dim nums = New Integer() {1, 2, 3}
Dim hero = New SuperHero With {.Name = "Batman"}
Type Information
Dim x As Integer
Console.WriteLine(x.GetType()) ' Prints System.Int32
Console.WriteLine(GetType(Integer)) ' Prints System.Int32
Console.WriteLine(TypeName(x)) ' Prints Integer
Dim c as New Circle
If TypeOf c Is Shape Then _
Console.WriteLine("c is a Shape")
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 o As Object = 2
i = DirectCast(o, Integer) ' Throws InvalidCastException if type cast fails
Dim s As New Shape
Dim c As Circle = TryCast(s, Circle) ' Returns Nothing if type cast fails
Value Types
bool
byte, sbyte
char
short, ushort, int, uint, long, ulong
float, double
decimal
DateTime (not a built-in C# type)
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("12/31/2010 12:15:00 PM");
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;
Implicitly Typed Local Variables
var s = "Hello!";
var nums = new int[] { 1, 2, 3 };
var hero = new SuperHero() { Name = "Batman" };
Type Information
int x;
Console.WriteLine(x.GetType()); // Prints System.Int32
Console.WriteLine(typeof(int)); // Prints System.Int32
Console.WriteLine(x.GetType().Name); // prints Int32
Circle c = new Circle();
if (c is Shape)
Console.WriteLine("c is a Shape");
Type Conversion / Casting
float d = 3.5f;
i = Convert.ToInt32(d); // Set to 4 (rounds)
int i = (int)d; // set to 3 (truncates decimal)
object o = 2;
int i = (int)o; // Throws InvalidCastException if type cast fails
Shape s = new Shape();
Circle c = s as Circle; // Returns null if type cast fails
VB.NET Constants C#
Const MAX_STUDENTS As Integer = 25
' Can set to a const or var; may be initialized in a constructor
ReadOnly MIN_DIAMETER As Single = 4.93
const int MAX_STUDENTS = 25;
// Can set to a const or var; may be initialized in a constructor
readonly float MIN_DIAMETER = 4.93f;
VB.NET Enumerations C#
Enum Action
Start
[Stop] ' Stop is a reserved word
Rewind
Forward
End Enum
Enum Status
Flunk = 50
Pass = 70
Excel = 90
End Enum
Dim a As Action = Action.Stop
If a <> Action.Start Then _
Console.WriteLine(a.ToString & " is " & a) ' Prints "Stop is 1"
Console.WriteLine(Status.Pass) ' Prints 70
Console.WriteLine(Status.Pass.ToString()) ' Prints Pass enum Action {Start, Stop, Rewind, Forward};
enum Status {Flunk = 50, Pass = 70, Excel = 90};
Action a = Action.Stop;
if (a != Action.Start)
Console.WriteLine(a + " is " + (int) a); // Prints "Stop is 1"
Console.WriteLine((int) Status.Pass); // Prints 70
Console.WriteLine(Status.Pass); // Prints Pass
VB.NET Operators C#
Comparison
= < > <= >= <>
Arithmetic
+ - * /
Mod
\ (integer division)
^ (raise to a power)
Assignment
= += -= *= /= \= ^= <<= >>= &=
Bitwise
And Or Xor Not << >>
Logical
AndAlso OrElse And Or Xor Not
Note: AndAlso and OrElse perform short-circuit logical evaluations
String Concatenation
&
Comparison
== < > <= >= !=
Arithmetic
+ - * /
% (mod)
/ (integer division if both operands are ints)
Math.Pow(x, y)
Assignment
= += -= *= /= %= &= |= ^= <<= >>= ++ --
Bitwise
& | ^ ~ << >>
Logical
&& || & | ^ !
Note: && and || perform short-circuit logical evaluations
String Concatenation
+
VB.NET Choices C#
' 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
// Ternary/Conditional operator
greeting = age < 20 ? "What's up?" : "Hello";
if (age < 20)
greeting = "What's up?";
else
greeting = "Hello";
// Multiple statements must be enclosed in {}
if (x != 100 && y < 5) {
x *= 5;
y *= 2;
}
No need for _ or : since ; is used to terminate each statement.
if (x > 5)
x *= y;
else if (x == 5 || y % 2 == 0)
x += y;
else if (x < 10)
x -= y;
else
x /= y;
// Every case must end with break or goto case
switch (color) { // Must be integer or string
case "pink":
case "red": r++; break;
case "blue": b++; break;
case "green": g++; break;
default: other++; break; // break necessary on default
}
VB.NET Loops C#
Pre-test Loops:
While c < 10
c += 1
End While
Do Until c = 10
c += 1
Loop
Do While c < 10
c += 1
Loop
For c = 2 To 10 Step 2
Console.WriteLine(c)
Next
Post-test Loops:
Do
c += 1
Loop While c < 10 Do
c += 1
Loop Until c = 10
' Array or collection looping
Dim names As String() = {"Fred", "Sue", "Barney"}
For Each s As String In names
Console.WriteLine(s)
Next
' Breaking out of loops
Dim i As Integer = 0
While (True)
If (i = 5) Then Exit While
i += 1
End While
' Continue to next iteration
For i = 0 To 4
If i < 4 Then Continue For
Console.WriteLine(i) ' Only prints 4
Next
Pre-test Loops:
// no "until" keyword
while (c < 10)
c++;
for (c = 2; c <= 10; c += 2)
Console.WriteLine(c);
Post-test Loop:
do
c++;
while (c < 10);
// Array or collection looping
string[] names = {"Fred", "Sue", "Barney"};
foreach (string s in names)
Console.WriteLine(s);
// Breaking out of loops
int i = 0;
while (true) {
if (i == 5)
break;
i++;
}
// Continue to next iteration
for (i = 0; i <= 4; i++) {
if (i < 4)
continue;
Console.WriteLine(i); // Only prints 4
}
VB.NET Arrays C#
Dim nums() As Integer = {1, 2, 3}
For i As Integer = 0 To nums.Length - 1
Console.WriteLine(nums(i))
Next
' 4 is the index of the last element, so it holds 5 elements
Dim names(4) As String
names(0) = "David"
names(5) = "Bobby" ' Throws System.IndexOutOfRangeException
' Resize the array, keeping the existing values (Preserve is optional)
ReDim Preserve names(6)
Dim twoD(rows-1, cols-1) As Single
twoD(2, 0) = 4.5
Dim jagged()() As Integer = { _
New Integer(4) {}, New Integer(1) {}, New Integer(2) {} }
jagged(0)(4) = 5
int[] nums = {1, 2, 3};
for (int i = 0; i < nums.Length; i++)
Console.WriteLine(nums[i]);
// 5 is the size of the array
string[] names = new string[5];
names[0] = "David";
names[5] = "Bobby"; // Throws System.IndexOutOfRangeException
// 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 Functions C#
' Pass by value (in, default), reference (in/out), and reference (out)
Sub TestFunc(ByVal x As Integer, ByRef y As Integer, ByRef z As Integer)
x += 1
y += 1
z = 5
End Sub
Dim a = 1, b = 1, c As Integer ' c set to zero by default
TestFunc(a, b, c)
Console.WriteLine("{0} {1} {2}", a, b, c) ' 1 2 5
' Accept variable number of arguments
Function Sum(ByVal ParamArray nums As Integer()) As Integer
Sum = 0
For Each i As Integer In nums
Sum += i
Next
End Function ' Or use Return statement like C#
Dim total As Integer = Sum(4, 3, 2, 1) ' returns 10
' Optional parameters must be listed last and must have a default value
Sub SayHello(ByVal name As String, Optional ByVal prefix As String = "")
Console.WriteLine("Greetings, " & prefix & " " & name)
End Sub
SayHello("Strangelove", "Dr.")
SayHello("Mom")
// Pass by value (in, default), reference (in/out), and reference (out)
void TestFunc(int x, ref int y, out int z) {
x++;
y++;
z = 5;
}
int a = 1, b = 1, c; // c doesn't need initializing
TestFunc(a, ref b, out c);
Console.WriteLine("{0} {1} {2}", a, b, c); // 1 2 5
// Accept variable number of arguments
int Sum(params int[] nums) {
int sum = 0;
foreach (int i in nums)
sum += i;
return sum;
}
int total = Sum(4, 3, 2, 1); // returns 10
/* C# 4.0 supports optional parameters. Previous versions required function overloading. */
void SayHello(string name, string prefix = "") {
Console.WriteLine("Greetings, " + prefix + " " + name);
}
SayHello("Strangelove", "Dr.");
SayHello("Mom");
VB.NET Strings C#
Special character constants (all also accessible from ControlChars class)
vbCrLf, vbCr, vbLf, vbNewLine
vbNullString
vbTab
vbBack
vbFormFeed
vbVerticalTab
""
' String concatenation (use & or +)
Dim school As String = "Harding" & vbTab
school = school & "University" ' school is "Harding (tab) University"
' 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 msg As String = "File is c:\temp\x.dat"
' String comparison
Dim mascot As String = "Bisons"
If (mascot = "Bisons") Then ' true
If (mascot.Equals("Bisons")) Then ' true
If (mascot.ToUpper().Equals("BISONS")) Then ' true
If (mascot.CompareTo("Bisons") = 0) Then ' true
' String matching with Like - Regex is more powerful
If ("John 3:16" Like "Jo[Hh]? #:*") Then 'true
' Substring
s = mascot.Substring(2, 3)) ' s is "son"
' Replacement
s = mascot.Replace("sons", "nomial")) ' s is "Binomial"
' Split
Dim names As String = "Michael,Dwight,Jim,Pam"
Dim parts() As String = names.Split(",".ToCharArray()) ' One name in each slot
' Date to string
Dim dt As New DateTime(1973, 10, 12)
Dim s As String = "My birthday: " & dt.ToString("MMM dd, yyyy") ' Oct 12, 1973
' Integer to String
Dim x As Integer = 2
Dim y As String = x.ToString() ' y is "2"
' String to Integer
Dim x As Integer = Convert.ToInt32("-5") ' x is -5
' Mutable string
Dim buffer As New System.Text.StringBuilder("two ")
buffer.Append("three ")
buffer.Insert(0, "one ")
buffer.Replace("two", "TWO")
Console.WriteLine(buffer) ' Prints "one TWO three"
Escape sequences
\r // carriage-return
\n // line-feed
\t // tab
\\ // backslash
\" // quote
// String concatenation
string school = "Harding\t";
school = school + "University"; // school is "Harding (tab) University"
// 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 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
// String matching - No Like equivalent, use Regex
// Substring
s = mascot.Substring(2, 3)) // s is "son"
// Replacement
s = mascot.Replace("sons", "nomial")) // s is "Binomial"
// Split
string names = "Michael,Dwight,Jim,Pam";
string[] parts = names.Split(",".ToCharArray()); // One name in each slot
// Date to string
DateTime dt = new DateTime(1973, 10, 12);
string s = dt.ToString("MMM dd, yyyy"); // Oct 12, 1973
// int to string
int x = 2;
string y = x.ToString(); // y is "2"
// string to int
int x = Convert.ToInt32("-5"); // x is -5
// Mutable string
System.Text.StringBuilder buffer = new System.Text.StringBuilder("two ");
buffer.Append("three ");
buffer.Insert(0, "one ");
buffer.Replace("two", "TWO");
Console.WriteLine(buffer); // Prints "one TWO three"
VB.NET Regular Expressions C#
Imports System.Text.RegularExpressions
' Match a string pattern
Dim r As New Regex("j[aeiou]h?. \d:*", RegexOptions.IgnoreCase Or _
RegexOptions.Compiled)
If (r.Match("John 3:16").Success) Then 'true
Console.WriteLine("Match")
End If
' Find and remember all matching patterns
Dim s As String = "My number is 305-1881, not 305-1818."
Dim r As New Regex("(\d+-\d+)")
Dim m As Match = r.Match(s) ' Matches 305-1881 and 305-1818
While m.Success
Console.WriteLine("Found number: " & m.Groups(1).Value & " at position " _
& m.Groups(1).Index.ToString)
m = m.NextMatch()
End While
' Remeber multiple parts of matched pattern
Dim r As New Regex("(\d\d):(\d\d) (am|pm)")
Dim m As Match = r.Match("We left at 03:15 pm.")
If m.Success Then
Console.WriteLine("Hour: " & m.Groups(1).ToString) ' 03
Console.WriteLine("Min: " & m.Groups(2).ToString) ' 15
Console.WriteLine("Ending: " & m.Groups(3).ToString) ' pm
End If
' Replace all occurrances of a pattern
Dim r As New Regex("h\w+?d", RegexOptions.IgnoreCase)
Dim s As String = r.Replace("I heard this was HARD!", "easy") ' I easy this was easy!
' Replace matched patterns
Dim s As String = Regex.Replace("123 < 456", "(\d+) . (\d+)", "$2 > $1") ' 456 > 123
' Split a string based on a pattern
Dim names As String = "Michael, Dwight, Jim, Pam"
Dim r As New Regex(",\s*")
Dim parts() As String = r.Split(names) ' One name in each slot
using System.Text.RegularExpressions;
// Match a string pattern
Regex r = new Regex(@"j[aeiou]h?. \d:*", RegexOptions.IgnoreCase |
RegexOptions.Compiled);
if (r.Match("John 3:16").Success) // true
Console.WriteLine("Match");
// Find and remember all matching patterns
string s = "My number is 305-1881, not 305-1818.";
Regex r = new Regex("(\\d+-\\d+)");
// Matches 305-1881 and 305-1818
for (Match m = r.Match(s); m.Success; m = m.NextMatch())
Console.WriteLine("Found number: " + m.Groups[1] + " at position " +
m.Groups[1].Index);
// Remeber multiple parts of matched pattern
Regex r = new Regex("@(\d\d):(\d\d) (am|pm)");
Match m = r.Match("We left at 03:15 pm.");
if (m.Success) {
Console.WriteLine("Hour: " + m.Groups[1]); // 03
Console.WriteLine("Min: " + m.Groups[2]); // 15
Console.WriteLine("Ending: " + m.Groups[3]); // pm
}
// Replace all occurrances of a pattern
Regex r = new Regex("h\\w+?d", RegexOptions.IgnoreCase);
string s = r.Replace("I heard this was HARD!", "easy")); // I easy this was easy!
// Replace matched patterns
string s = Regex.Replace("123 < 456", @"(\d+) . (\d+)", "$2 > $1"); // 456 > 123
// Split a string based on a pattern
string names = "Michael, Dwight, Jim, Pam";
Regex r = new Regex(@",\s*");
string[] parts = r.Split(names); // One name in each slot
VB.NET Exception Handling C#
' Throw an exception
Dim ex As New Exception("Something is really wrong.")
Throw ex
' Catch an exception
Try
y = 0
x = 10 / y
Catch ex As Exception When y = 0 ' Argument and When is optional
Console.WriteLine(ex.Message)
Finally
Beep()
End Try
' Deprecated unstructured error handling
On Error GoTo MyErrorHandler
...
MyErrorHandler: Console.WriteLine(Err.Description)
// Throw an exception
Exception up = new Exception("Something is really wrong.");
throw up; // ha ha
// Catch an exception
try {
y = 0;
x = 10 / y;
}
catch (Exception ex) { // Argument is optional, no "When" keyword
Console.WriteLine(ex.Message);
}
finally {
Microsoft.VisualBasic.Interaction.Beep();
}
VB.NET Namespaces C#
Namespace Harding.Compsci.Graphics
...
End Namespace
' or
Namespace Harding
Namespace Compsci
Namespace Graphics
...
End Namespace
End Namespace
End Namespace
Imports Harding.Compsci.Graphics
namespace Harding.Compsci.Graphics {
...
}
// or
namespace Harding {
namespace Compsci {
namespace Graphics {
...
}
}
}
using Harding.Compsci.Graphics;
VB.NET Classes / Interfaces C#
Access Modifiers
Public
Private
Friend
Protected
Protected Friend
Class Modifiers
MustInherit
NotInheritable
Method Modifiers
MustOverride
NotInheritable
Shared
Overridable
' All members are Shared
Module
' Partial classes
Partial Class Competition
...
End Class
' Inheritance
Class FootballGame
Inherits Competition
...
End Class
' Interface definition
Interface IAlarmClock
Sub Ring()
Property TriggerDateTime() As DateTime
End Interface
' Extending an interface
Interface IAlarmClock
Inherits IClock
...
End Interface
' Interface implementation
Class WristWatch
Implements IAlarmClock, ITimer
Public Sub Ring() Implements IAlarmClock.Ring
Console.WriteLine("Wake up!")
End Sub
Public Property TriggerDateTime As DateTime Implements IAlarmClock.TriggerDateTime
...
End Class
Access Modifiers
public
private
internal
protected
protected internal
Class Modifiers
abstract
sealed
static
Method Modifiers
abstract
sealed
static
virtual
No Module equivalent - just use static class
// Partial classes
partial class Competition {
...
}
// Inheritance
class FootballGame : Competition {
...
}
// Interface definition
interface IAlarmClock {
void Ring();
DateTime CurrentDateTime { get; set; }
}
// Extending an interface
interface IAlarmClock : IClock {
...
}
// Interface implementation
class WristWatch : IAlarmClock, ITimer {
public void Ring() {
Console.WriteLine("Wake up!");
}
public DateTime TriggerDateTime { get; set; }
...
}
VB.NET Constructors / Destructors C#
Class SuperHero
Private powerLevel As Integer
Public Sub New()
powerLevel = 0
End Sub
Public Sub New(ByVal powerLevel As Integer)
Me.powerLevel = powerLevel
End Sub
Shared Sub New()
' Shared constructor invoked before 1st instance is created
End Sub
Protected Overrides Sub Finalize()
' Destructor to free unmanaged resources
MyBase.Finalize()
End Sub
End Class
class SuperHero {
private int powerLevel;
public SuperHero() {
powerLevel = 0;
}
public SuperHero(int powerLevel) {
this.powerLevel = powerLevel;
}
static SuperHero() {
// Static constructor invoked before 1st instance is created
}
~SuperHero() {
// Destructor implicitly creates a Finalize method
}
}
VB.NET Using Objects C#
Dim hero As SuperHero = New SuperHero
' or
Dim hero As New SuperHero
With hero
.Name = "SpamMan"
.PowerLevel = 3
End With
hero.Defend("Laura Jones")
hero.Rest() ' Calling Shared method
' or
SuperHero.Rest()
Dim hero2 As SuperHero = hero ' Both reference the same object
hero2.Name = "WormWoman"
Console.WriteLine(hero.Name) ' Prints WormWoman
hero = Nothing ' Free the object
If hero Is Nothing Then _
hero = New SuperHero
Dim obj As Object = New SuperHero
If TypeOf obj Is SuperHero Then _
Console.WriteLine("Is a SuperHero object.")
' Mark object for quick disposal
Using reader As StreamReader = File.OpenText("test.txt")
Dim line As String = reader.ReadLine()
While Not line Is Nothing
Console.WriteLine(line)
line = reader.ReadLine()
End While
End Using
SuperHero hero = new SuperHero();
// No "With" 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);
}
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 Properties C#
' Auto-implemented properties are new to VB10
Public Property Name As String
Public Property Size As Integer = -1 ' Default value, Get and Set both Public
' Traditional property implementation
Private mName As String
Public Property Name() As String
Get
Return mName
End Get
Set(ByVal value As String)
mName = value
End Set
End Property
' Read-only property
Private mPowerLevel As Integer
Public ReadOnly Property PowerLevel() As Integer
Get
Return mPowerLevel
End Get
End Property
' Write-only property
Private mHeight As Double
Public WriteOnly Property Height() As Double
Set(ByVal value As Double)
mHeight = If(value < 0, mHeight = 0, mHeight = value)
End Set
End Property
// Auto-implemented properties
public string Name { get; set; }
public int Size { get; protected set; } // Set default value in constructor
// Traditional property implementation
private string name;
public string Name {
get {
return name;
}
set {
name = value;
}
}
// Read-only property
private int powerLevel;
public int PowerLevel {
get {
return powerLevel;
}
}
// Write-only property
private double height;
public double Height {
set {
height = value < 0 ? 0 : value;
}
}
VB.NET Delegates / Events C#
Delegate Sub MsgArrivedEventHandler(ByVal message As String)
Event MsgArrivedEvent As MsgArrivedEventHandler
' or to define an event which declares a delegate implicitly
Event MsgArrivedEvent(ByVal message As String)
AddHandler MsgArrivedEvent, AddressOf My_MsgArrivedCallback
' Won't throw an exception if obj is Nothing
RaiseEvent MsgArrivedEvent("Test message")
RemoveHandler MsgArrivedEvent, AddressOf My_MsgArrivedCallback
Imports System.Windows.Forms
Dim WithEvents MyButton As Button ' WithEvents can't be used on local variable
MyButton = New Button
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 Generics C#
' Enforce accepted data type at compile-time
Dim numbers As New List(Of Integer)
numbers.Add(2)
numbers.Add(4)
DisplayList(Of Integer)(numbers)
' Subroutine can display any type of List
Sub DisplayList(Of T)(ByVal list As List(Of T))
For Each item As T In list
Console.WriteLine(item)
Next
End Sub
' Class works on any data type
Class SillyList(Of T)
Private list(10) As T
Private rand As New Random
Public Sub Add(ByVal item As T)
list(rand.Next(10)) = item
End Sub
Public Function GetItem() As T
Return list(rand.Next(10))
End Function
End Class
' Limit T to only types that implement IComparable
Function Maximum(Of T As IComparable)(ByVal ParamArray items As T()) As T
Dim max As T = items(0)
For Each item As T In items
If item.CompareTo(max) > 0 Then max = item
Next
Return max
End Function
// Enforce accepted data type at compile-time
List<int> numbers = new List<int>();
numbers.Add(2);
numbers.Add(4);
DisplayList<int>(numbers);
// Function can display any type of List
void DisplayList<T>(List<T> list) {
foreach (T item in list)
Console.WriteLine(item);
}
// Class works on any data type
class SillyList<T> {
private T[] list = new T[10];
private Random rand = new Random();
public void Add(T item) {
list[rand.Next(10)] = item;
}
public T GetItem() {
return list[rand.Next(10)];
}
}
// Limit T to only types that implement IComparable
T Maximum<T>(params T[] items) where T : IComparable<T> {
T max = items[0];
foreach (T item in items)
if (item.CompareTo(max) > 0)
max = item;
return max;
}
VB.NET LINQ C#
Dim nums() As Integer = {5, 8, 2, 1, 6}
' Get all numbers in the array above 4
Dim results = From value In nums
Where value > 4
Select value
Console.WriteLine(results.Count()) ' 3
Console.WriteLine(results.First()) ' 5
Console.WriteLine(results.Last()) ' 6
Console.WriteLine(results.Average()) ' 6.33333
' Displays 5 8 6
For Each n As Integer In results
Console.Write(n & " ")
Next
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 an ordered list of all students by GPA with GPA >= 3.0
Dim goodStudents = From s In Students
Where s.GPA >= 3.0
Order By s.GPA Descending
Select s
Console.WriteLine(goodStudents.First.Name) ' Sue
int[] nums = { 5, 8, 2, 1, 6 };
// Get all numbers in the array above 4
var results = from value in nums
where value > 4
select value;
Console.WriteLine(results.Count()); // 3
Console.WriteLine(results.First()); // 5
Console.WriteLine(results.Last()); // 6
Console.WriteLine(results.Average()); // 6.33333
// Displays 5 8 6
foreach (int n in results)
Console.Write(n + " ");
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 an ordered list of all students by GPA with GPA >= 3.0
var goodStudents = from s in Students
where s.GPA >= 3.0
orderby s.GPA descending
select s;
Console.WriteLine(goodStudents.First().Name); // Sue
VB.NET Console I/O C#
Console.Write("What's your name? ")
Dim name As String = Console.ReadLine()
Console.Write("How old are you? ")
Dim age As Integer = Val(Console.ReadLine())
Console.WriteLine("{0} is {1} years old.", name, age)
' or
Console.WriteLine(name & " is " & age & " years old.")
Dim c As Integer
c = Console.Read() ' Read single char
Console.WriteLine(c) ' Prints 65 if user enters "A"
Console.Write("What's your name? ");
string name = Console.ReadLine();
Console.Write("How old are you? ");
int age = Convert.ToInt32(Console.ReadLine());
Console.WriteLine("{0} is {1} years old.", name, age);
// or
Console.WriteLine(name + " is " + age + " years old.");
int c = Console.Read(); // Read single char
Console.WriteLine(c); // Prints 65 if user enters "A"
VB.NET File I/O C#
Imports System.IO
' Write out to text file
Dim writer As StreamWriter = File.CreateText("c:\myfile.txt")
writer.WriteLine("Out to file.")
writer.Close()
' Read all lines from text file
Dim reader As StreamReader = File.OpenText("c:\myfile.txt")
Dim line As String = reader.ReadLine()
While Not line Is Nothing
Console.WriteLine(line)
line = reader.ReadLine()
End While
reader.Close()
' Write out to binary file
Dim str As String = "Text data"
Dim num As Integer = 123
Dim binWriter As New BinaryWriter(File.OpenWrite("c:\myfile.dat"))
binWriter.Write(str)
binWriter.Write(num)
binWriter.Close()
' Read from binary file
Dim binReader As New BinaryReader(File.OpenRead("c:\myfile.dat"))
str = binReader.ReadString()
num = binReader.ReadInt32()
binReader.Close()
using System.IO;
// Write out to text file
StreamWriter writer = File.CreateText("c:\\myfile.txt");
writer.WriteLine("Out to file.");
writer.Close();
// Read all lines from text file
StreamReader reader = File.OpenText("c:\\myfile.txt");
string line = reader.ReadLine();
while (line != null) {
Console.WriteLine(line);
line = reader.ReadLine();
}
reader.Close();
// Write out to binary file
string str = "Text data";
int num = 123;
BinaryWriter binWriter = new BinaryWriter(File.OpenWrite("c:\\myfile.dat"));
binWriter.Write(str);
binWriter.Write(num);
binWriter.Close();
// Read from binary file
BinaryReader binReader = new BinaryReader(File.OpenRead("c:\\myfile.dat"));
str = binReader.ReadString();
num = binReader.ReadInt32();
binReader.Close();
