unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}


//这是一个过程, 过程没有返回值
procedure MyProc(var x: Integer);
begin
  x := x * 2;
end;

//这是一个函数, 函数必须有返回值
function MyFun(var x: Integer): Integer;
begin
  x := x * 2;
  Result := x;
end;


//调用过程与函数
procedure TForm1.Button1Click(Sender: TObject);
var
  i: Integer;
begin
  i := 6;
  MyProc(i);                {使用过程}
  ShowMessage(IntToStr(i)); {12}

  i := 6;
  i := MyFun(i);            {使用函数}
  ShowMessage(IntToStr(i)); {12}
end;

end.

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

Type
  TMyClass = class
    procedure MyProc(var x: Integer);
    function  MyFun (var x: Integer): Integer;
  end;
{
  上面定义了一个类, 其中包含了两个方法;
  函数与过程来到类里面一般叫做方法, 函数是有返回值的方法、过程是没有返回值的方法;

  在这里, 方法只有定义没有实现;
  但必须在本单元的 implementation 区内实现.

  下面就是两个方法的实现:
}

function TMyClass.MyFun(var x: Integer): Integer;
begin
  x := x * 2;
  Result := x;
end;

procedure TMyClass.MyProc(var x: Integer);
begin
  x := x * 2;
end;



//调用测试
procedure TForm1.Button1Click(Sender: TObject);
var
  i: Integer;
  myClass: TMyClass;          {对象声明}
begin
  myClass := TMyClass.Create; {对象建立}

  i := 6;
  myClass.MyProc(i);          {调用方法}
  ShowMessage(IntToStr(i));   {12}

  i := 6;
  i := myClass.MyFun(i);      {调用方法}
  ShowMessage(IntToStr(i));   {12}

  myClass.Free;               {对象释放}
end;

end.

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  end;

  {类定义, 因为已经在 Type 区了, 可以省略 Type 关键字}
  TMyClass = class
    procedure MyProc(var x: Integer);
    function  MyFun (var x: Integer): Integer;
  end;


var
  Form1: TForm1;

implementation

{$R *.dfm}


{TMyClass 中方法的实现}

function TMyClass.MyFun(var x: Integer): Integer;
begin
  x := x * 2;
  Result := x;
end;

procedure TMyClass.MyProc(var x: Integer);
begin
  x := x * 2;
end;



//调用测试
procedure TForm1.Button1Click(Sender: TObject);
var
  i: Integer;
  myClass: TMyClass;          {对象声明}
begin
  myClass := TMyClass.Create; {对象建立}

  i := 6;
  myClass.MyProc(i);          {调用方法}
  ShowMessage(IntToStr(i));   {12}

  i := 6;
  i := myClass.MyFun(i);      {调用方法}
  ShowMessage(IntToStr(i));   {12}

  myClass.Free;               {对象释放}
end;

end.