C# 与 VB.NET 对比
2008-06-20 15:30 by Anders Cui, 1462 阅读, 3 评论, 收藏, 编辑
2.15Constructors / Destructors
1.0 Introduction
1.1 Purpose & Scope
This document is to compare the syntax between the VB.Net and C#.Net for various coding concepts.
2.0 Comparison
2.1 Program Structure
VB.NET |
C#.NET |
Imports System Namespace Hello 'See if an argument was passed from the command line Console.WriteLine("Hello, " & name & "!") |
using System; namespace Hello { // See if an argument was passed from the command line Console.WriteLine("Hello, " + name + "!"); |
2.2 Comments
VB.NET |
C#.NET |
' Single line only |
// Single line |
2.3 Data Types
VB.NET |
C#.NET |
Value Types Reference Types Initializing Type Information Type Conversion |
Value Types Reference Types Initializing object person = null; Type Information Type Conversion |
2.4 Constants
VB.NET |
C#.NET |
Const MAX_STUDENTS As Integer = 25 ' Can set to a const or var; may be initialized in a constructor |
const int MAX_STUDENTS = 25; // Can set to a const or var; may be initialized in a constructor |
2.5 Enumerations
VB.NET |
C#.NET |
Enum Action Enum Status Console.WriteLine(Status.Pass) ' Prints 70 |
enum Action {Start, Stop, Rewind, Forward}; Action a = Action.Stop; Console.WriteLine((int) Status.Pass); // Prints 70 |
2.6 Operators
VB.NET |
C#.NET |
Comparison Arithmetic Assignment Bitwise Logical Note: AndAlso and OrElse perform short-circuit logical evaluations String Concatenation |
Comparison Arithmetic Assignment Bitwise Logical Note: && and || perform short-circuit logical evaluations String Concatenation |
2.7 Choices
VB.NET |
C#.NET |
greeting = IIf(age < 20, "What's up?", "Hello") ' One line doesn't require "End If" ' Use : to put two commands on same line ' Preferred ' To break up any long single line use _ 'If x > 5 Then Select Case color ' Must be a primitive data type |
greeting = age < 20 ? "What's up?" : "Hello"; if (age < 20) // Multiple statements must be enclosed in {} No need for _ or : since ; is used to terminate each statement. if (x > 5) // Every case must end with break or goto case |
2.8 Loops
VB.NET |
C#.NET |
||||||
Pre-test Loops:
Post-test Loops:
' Array or collection looping ' Breaking out of loops ' Continue to next iteration |
Pre-test Loops: // no "until" keyword for (c = 2; c <= 10; c += 2) Post-test Loop: do // Array or collection looping // Breaking out of loops // Continue to next iteration |
2.9 Arrays
VB.NET |
C#.NET |
Dim nums() As Integer = {1, 2, 3} ' 4 is the index of the last element, so it holds 5 elements ' Resize the array, keeping the existing values (Preserve is optional) Dim twoD(rows-1, cols-1) As Single Dim jagged()() As Integer = { _ |
int[] nums = {1, 2, 3}; // 5 is the size of the array // C# can't dynamically resize an array. Just copy into new array. float[,] twoD = new float[rows, cols]; int[][] jagged = new int[3][] { |
2.10 Functions
VB.NET |
C#.NET |
' Pass by value (in, default), reference (in/out), and reference (out) Dim a = 1, b = 1, c As Integer ' c set to zero by default ' Accept variable number of arguments Dim total As Integer = Sum(4, 3, 2, 1) ' returns 10 ' Optional parameters must be listed last and must have a default value SayHello("Strangelove", "Dr.") |
// Pass by value (in, default), reference (in/out), and reference (out) int a = 1, b = 1, c; // c doesn't need initializing // Accept variable number of arguments 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) { |
2.11 Strings
VB.NET |
C#.NET |
Special character constants ' String concatenation (use & or +) ' Chars ' No string literal operator ' String comparison Console.WriteLine(mascot.Substring(2, 3)) ' Prints "son" ' String matching Imports System.Text.RegularExpressions ' More powerful than Like ' My birthday: Oct 12, 1973 ' Mutable string |
Escape sequences // String concatenation // Chars // String literal // String comparison Console.WriteLine(mascot.Substring(2, 3)); // Prints "son" // String matching using System.Text.RegularExpressions; // My birthday: Oct 12, 1973 // Mutable string |
2.12 Exception Handling
VB.NET |
C#.NET |
' Throw an exception ' Catch an exception ' Deprecated unstructured error handling |
// Throw an exception // Catch an exception |
2.13 Namespaces
VB.NET |
C#.NET |
Namespace Harding.Compsci.Graphics ' or Namespace Harding Imports Harding.Compsci.Graphics |
namespace Harding.Compsci.Graphics { // or namespace Harding { using Harding.Compsci.Graphics; |
2.14 Classes / Interfaces
VB.NET |
C#.NET |
Accessibility keywords ' Inheritance ' Interface definition // Extending an interface // Interface implementation |
Accessibility keywords // Inheritance
// Extending an interface
|
2.15 Constructors / Destructors
VB.NET |
C#.NET |
Class SuperHero Public Sub New() Public Sub New(ByVal powerLevel As Integer) Protected Overrides Sub Finalize() |
class SuperHero { public SuperHero() { public SuperHero(int powerLevel) { ~SuperHero() { |
2.16 Using Objects
VB.NET |
C#.NET |
Dim hero As SuperHero = New SuperHero With hero hero.Defend("Laura Jones") Dim hero2 As SuperHero = hero ' Both reference the same object hero = Nothing ' Free the object If hero IsNothing Then _ Dim obj As Object = New SuperHero ' Mark object for quick disposal |
SuperHero hero = new SuperHero(); // No "With" construct hero.Defend("Laura Jones"); SuperHero hero2 = hero; // Both reference the same object hero = null ; // Free the object if (hero == null) Object obj = new SuperHero(); // Mark object for quick disposal |
2.17 Structs
VB.NET |
C#.NET |
Structure StudentRecord Public Sub New(ByVal name As String, ByVal gpa As Single) Dim stu As StudentRecord = New StudentRecord("Bob", 3.5) stu2.name = "Sue" |
struct StudentRecord { public StudentRecord(string name, float gpa) { StudentRecord stu = new StudentRecord("Bob", 3.5f); stu2.name = "Sue"; |
2.18 Properties
VB.NET |
C#.NET |
Private _size As Integer Public Property Size() As Integer foo.Size += 1 |
private int _size; public int Size { foo.Size++; |
2.19 Delegates / Events
VB.NET |
C#.NET |
Delegate Sub MsgArrivedEventHandler(ByVal message As String) Event MsgArrivedEvent As MsgArrivedEventHandler ' or to define an event which declares a delegate implicitly AddHandler MsgArrivedEvent, AddressOfMy_MsgArrivedCallback Imports System.Windows.Forms Dim WithEvents MyButton As Button ' WithEvents can't be used on local variable Private Sub MyButton_Click(ByVal sender As System.Object, _ |
delegate void MsgArrivedEventHandler(string message); event MsgArrivedEventHandler MsgArrivedEvent; // Delegates must be used with events in C# MsgArrivedEvent += new MsgArrivedEventHandler(My_MsgArrivedEventCallback); using System.Windows.Forms; Button MyButton = new Button(); private void MyButton_Click(object sender, System.EventArgs e) { |
2.20 Console I/O
VB.NET |
C#.NET |
Console.Write("What's your name? ") Dim c As Integer |
Console.Write("What's your name? "); int c = Console.Read(); // Read single char |
2.21 File I/O
VB.NET |
C#.NET |
Imports System.IO ' Write out to text file ' Read all lines from text file ' Write out to binary file ' Read from binary file |
using System.IO; // Write out to text file // Read all lines from text file // Write out to binary file // Read from binary file |
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