DELPHI7与C#语法比较

DELPHI and C# Comparison

DELPHI7与C#语法比较
编制：黄焕尧      参考：VB.net and C# Comparison     日期：2005-5-30.

 

Comments 注释 Data Types数据类 Constants 常量 Enumerations 枚举 Operators 运算

Choices 选择语句 Loops 循环语句 Arrays 数组 Functions 函数 Exception Handling 异常处理

Namespaces 命名空间 Classes / Interfaces Constructors / Destructors 构造/释构 Objects 对象 Structs 结构

Properties 属性 Delegates / Events Console I/O File I/O

 

DELPHI	C#
Comments注释
// Single line only { Multiple line  } （* Multiple line  *）	// Single line /* Multiple     line  */ /// XML comments on single line /** XML comments on multiple lines */
Data Types 数据类型
Value Types 简单类型 Boolean Byte Char   (example: "A"c) Word, Integer, Int64 Real ,Single, Double,Real48,Extended,Comp,Currency Decimal Tdate,TDateTime Reference Types Object String(ShortString,AnsiString,WideString) Set, array, record, file,class,class reference,interface pointer, procedural, variant var x:Integer;  WriteLine(x);     // Prints System.Int32  WriteLine(‘Ingeger’);  // Prints Integer // Type conversion var numDecimal:Single = 3.5 ; var numInt:Integer; numInt :=Integer(numDecimal)   // set to 4 (Banker's rounding)  the decimal)	Value Types bool byte, sbyte char   (example: 'A') short, ushort, int, uint, long, ulong float, double decimal DateTime   (not a built-in C# type) Reference Types object string   int x; Console.WriteLine(x.GetType());    // Prints System.Int32 Console.WriteLine(typeof(int));      // Prints System.Int32 // Type conversion double numDecimal = 3.5; int numInt = (int) numDecimal;   // set to 3  (truncates decimal)
Constants常量
Const MAX_STUDENTS：Integer = 25；	const int MAX_STUDENTS = 25;
Enumerations枚举
Type Taction1=(Start, Stop, Rewind, Forward); {$M+} Type Status=(Flunk = 50, Pass = 70, Excel = 90);  {$M-} var a:Taction1 = Stop; If a <>Start Then  WriteLn(ord(a));     // Prints 1  WriteLine(Ord(Pass));     // Prints 70  WriteLine(GetEnumName(TypeInfo(Status),Ord(Pass)));   // Prints Pass ShowEnum(Pass); //outputs 70 GetEnumValue(GetEnumName(TypeInfo(Status),’Pass’));//70	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(Status.Pass);    // Prints Pass
Operators运算符
Comparison  比较 =  <  >  <=  >=  <>  in  as Arithmetic 算述述运算 +  -  *  /  div Mod /  (integer division) ^  (raise to a power) 阶乘 Assignment 赋值分配 :=  Inc()  Dec()   shl  shr  Bitwise 位运算 and  xor  or    not  shl  shr //Logical and  xor  or    not   //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 +
Choices 判断
greeting := IfThen (age < 20, ‘What's up?’, ‘Hello’)；   If language = ‘DELPHI’ Then   langType := ‘hymnlan’; // If x <> 100 Then begin   x := x*5 ; y :=x* 2;   end; // or to break up any long single command use _ If (whenYouHaveAReally < longLine  and itNeedsToBeBrokenInto2 > Lines Then    UseTheUnderscore(charToBreakItUp); 'If x > 5 Then   x :=x* y Else If x = 5 Then   x :=x+ y Else If x < 10 Then   x :=x- y Else   x :=x/ y ; Case color of  // 不能为字符串类型   pink, red:       r :=r+ 1;   blue:     b :=b+1;   green:     g :=g+ 1;   Else     Inc(other);  End;	greeting = age < 20 ? "What's up?" : "Hello";     if (x != 100) {    // Multiple statements must be enclosed in {}   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; switch (color) {                          // Must be integer or string   case "pink":   case "red":    r++;    break;        // break is mandatory; no fall-through   case "blue":   b++;   break;   case "green": g++;   break;   default:    other++;   break;       // break necessary on default }
Loops 循环
Pre-test Loops: While c < 10 do   Inc(c) ; End For c = 2 To 10 do   WriteLn(IntToStr(c)); For c = 10 DownTo 2  do   WriteLn(IntToStr(c));   repeat   Inc(c); Until c = 10 ; //  Array or collection looping count names:array[] of String = (‘Fred’, ‘Sue’, ‘Barney’) For i:=low(name) to High(name) do   WriteLn(name[i]); DELPHI8开始支持 for … each … 语法	Pre-test Loops:   // no "until" keyword while (i < 10)   i++; for (i = 2; i < = 10; i += 2)   Console.WriteLine(i); Post-test Loop: do   i++; while (i < 10); // Array or collection looping string[] names = {"Fred", "Sue", "Barney"}; foreach (string s in names)   Console.WriteLine(s);
Arrays 数组
var nums:array[] of Integer = (1, 2, 3)  For i := 0 To High(nums) do   WriteLn(IntToStr(nums[i])) // 4 is the index of the last element, so it holds 5 elements var names:array[0..5] of String; //用子界指定数组范围 names[0] = "David" names[5] = "Bobby"  // Resize the array, keeping the existing values SetLength(names,6); var twoD:array[rows-1, cols-1] of Single; twoD[2, 0] := 4.5; var jagged:array[] of Integer =((0,0,0,0),(0,0,0,0));   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# doesn't 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;
Functions函数
' Pass by value（传值参数） (in, default), 传递引用参数reference (in/out), and reference (out)  procedure TestFunc( x:Integer, var y:Integer, var z:Integer) ; begin   x :=x+1;   y :=y+1;   z := 5; End; count a = 1;  var b:integer=1; c :Integer=0;   // c set to zero by default  TestFunc(a, b, c);   WriteLn(Format(‘%d %d %d’,[a, b, c]);   // 1 2 5 // Accept variable number of arguments Function Sum(nums:array[] of Integer):Integer; begin   Result := 0;    For i:=Low(nums) to high(nums) do     Result := Result + I;    End   var total :Integer; total := Sum(4, 3, 2, 1);   // returns 10 // Optional parameters must be listed last and must have a default value procedure SayHello( name:String;prefix:String = ‘’); begin   WriteLn(‘Greetings, ‘ + prefix + ‘ ‘ + name); End; SayHello(‘Strangelove’, ‘Dr.’); SayHello(‘Madonna’);	// Pass by value (in, default), reference (in/out), and reference (out) void TestFunc(int x, ref int y, out int z) {   x++;     y++;   z = 5; } int a = 1, b = 1, c;  // c doesn't need initializing TestFunc(a, ref b, out c); Console.WriteLine("{0} {1} {2}", a, b, c);  // 1 2 5 // Accept variable number of arguments int Sum(params int[] nums) {   int sum = 0;   foreach (int i in nums)     sum += i;   return sum; } int total = Sum(4, 3, 2, 1);   // returns 10 /* C# doesn't support optional arguments/parameters.  Just create two different versions of the same function. */  void SayHello(string name, string prefix) {   Console.WriteLine("Greetings, " + prefix + " " + name); }  void SayHello(string name) {   SayHello(name, ""); }
Exception Handling 异常处理
' Deprecated unstructured error handling var ex :TException; ex:=TException.Create(‘Something is really wrong.’);   Try    //DELPHI 不支持异常捕捉与Finally同时使用 Try    y = 0   x = 10 / y except  ON  Ex:Exception   begin   if y = 0  then '     WriteLn(ex.Message) ; end; Finally   Beep(); End;	Exception up = new Exception("Something is really wrong."); throw up;  // ha ha try {    y = 0;   x = 10 / y; } catch (Exception ex) {   // Argument is optional, no "When" keyword    Console.WriteLine(ex.Message); } finally {   // Must use unmanaged MessageBeep API function to beep }
Namespaces 命名空间
//delphi无命名空间，以单元与之对应 Unit  Harding；    ... End.       uses Harding;	namespace Harding.Compsci.Graphics {   ... } // or namespace Harding {   namespace Compsci {     namespace Graphics {       ...     }   } } using Harding.Compsci.Graphics;
Classes / Interfaces 类和接口
Accessibility keywords 界定关键字 Public Private                    Protected published // Protected Type FootballGame= Class     Protected     Competition:string;   ...  End // Interface definition Type IalarmClock= Interface (IUnknown)     ... End // end Interface // Extending an interface  Type IalarmClock= Interface (IUnknown)  ['{00000115-0000-0000-C000-000000000044}']   function Iclock:Integer;   ... End //end Interface // Interface implementation Type WristWatch=Class(TObject, IAlarmClock ,ITimer)   function Iclock:Integer;    ... End	Accessibility keywords public private internal protected protected internal static // Inheritance class FootballGame : Competition {   ... } // Interface definition interface IAlarmClock {   ... } // Extending an interface  interface IAlarmClock : IClock {   ... } // Interface implementation class WristWatch : IAlarmClock, ITimer {    ... }
Constructors / Destructors构造/释构
Type SuperHero=Class   Private      ApowerLevel:Integer;   Public     constructor Create;override;     constructor New(powerLevel:Integer); virtual;     destructor Destroy; override; end; //end Class Interface Implementation procedure Create(); begin   ApowerLevel := 0; end; procedure New(powerLevel:Integer); begin   self.ApowerLevel := powerLevel; end; procedure Destroy; begin   …   inherited Destroy; end End.	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   } }
Objects 对象
var hero:SuperHero;  hero := SuperHero.Create; With hero   Name := "SpamMan";   PowerLevel := 3; End //end With hero.Defend(‘Laura Jones’); hero.Rest();     // Calling Shared method // or SuperHero.Rest(); var hero2:SuperHero; hero2:= hero;  // Both refer to same object hero2.Name := ‘WormWoman’;  WriteLn(hero.Name)   // Prints WormWoman hero.Free; hero = nil;    // Free the object if hero= nil then    hero := SuperHero.Create; var obj:Object;  obj:= SuperHero.Create; if obj is SuperHero then  WriteLn(‘Is a SuperHero object.’);	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 refer to 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.");
Structs记录/结构
Type StudentRecord = packed Record    name:String;    gpa:Single; End //end Structure Var stu:StudentRecord; stu.name:=’Bob; stu:=3.5; var stu2:StudentRecord; stu2 := stu;   stu2.name := ‘Sue’;  WriteLn(stu.name)    // Prints Bob  WriteLn(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
Properties属性
Private Asize：Integer； Published Property Size：Integer read GetSize write SetSize; End; Implementation Function GetSize:Integer; begin   Result:=Asize; end; procedure SetSize(Value:Integer); begin   if Value<0 then     Asize := 0   else     Asuze := Value; end; foo.Size := foo.Size + 1;	private int _size; public int Size {   get {     return _size;   }   set {     if (value < 0)       _size = 0;     else       _size = value;   } } foo.Size++;
Delegates / Events事件
Type   MsgArrivedEventHandler=prcedure(message:string) of object; MsgArrivedEvent:MsgArrivedEventHandler;   Type MyButton =Class(Tbutton)  private   FClick:MsgArrivedEventHandler;  public   procedure Click;   property onClick:MsgArrivedEventHandler read Fclick write Fclick; end; Implementation Procedure MyButton.Click; begin   MessageBox (self.handle, ‘Button was clicked’, ‘Info’,     MessageBoxButtonsOK, MessageBoxIconInformation); end;	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); }
Console I/O
DELPHI无控制台对象 若为控制台程序则 Write(count Text); WriteLn(count Text); Read(var Text); ReadLn(var Text);	Escape sequences /n, /r /t // /" Convert.ToChar(65)  // Returns 'A' - equivalent to Chr(num) in VB // or (char) 65 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"
File I/O
//uses System Var fwriter: TextFile; AssignFile (fwriter,’c:/myfile.txt’); fwriter.WriteLn(‘Out to file.’); CloseFile(fwriter); var reader:TextFile; line:String; AssignFile(reader ,‘c:/myfile.txt’); Readln(reader ,line); While Not (line=’’) do begin   WriteLn(‘line=’ + line);   Readln(reader ,line); End;  CloseFile(reader); var str:String = ‘Text data’; var num :Integer = 123; var binWriter: TfileStream; binWriter:= TFileStream.Create(‘c:/myfile.dat’, fmCreate or fmOpenWrite); try   binWriter.Write(str,sizeof(str));    binWriter.Write(num,sizeof(num));  finally   binWriter.Free; end; var binReader: TFileStream; binReader :=TFileStream.Create(‘c:/myfile.dat’, fmOpenRead or mShareDenyRead); try   binReader.Read(str,sizeof(str));   binReader.Read(num,sizeof(num)); finally   binReader.Free; end;	using System.IO; StreamWriter writer = File.CreateText("c://myfile.txt"); writer.WriteLine("Out to file."); writer.Close(); StreamReader reader = File.OpenText("c://myfile.txt"); string line = reader.ReadLine(); while (line != null) {   Console.WriteLine(line);   line = reader.ReadLine(); } reader.Close(); string str = "Text data"; int num = 123; BinaryWriter binWriter = new BinaryWriter(File.OpenWrite("c://myfile.dat")); binWriter.Write(str); binWriter.Write(num); binWriter.Close(); BinaryReader binReader = new BinaryReader(File.OpenRead("c://myfile.dat")); str = binReader.ReadString(); num = binReader.ReadInt32(); binReader.Close();