简易计算器

 

unit Unit1_test;

interface

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

type
  TForm1 = class(TForm)
    Edit1: TEdit;
    Edit2: TEdit;
    ComboBox1: TComboBox;
    Button1: TButton;
    Label1: TLabel;
    procedure Button1Click(Sender: TObject);
    function MyCalculator(var a,b:Real):Real;
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
var
  a,b:Real;
  result1:Real;
begin
  a:=StrToFloat(Edit1.Text);
  b:=StrToFloat(Edit2.Text);
  result1:=MyCalculator(a,b);
  Label1.Caption:=FloatToStr(result1);
end;


function TForm1.MyCalculator(var a, b: Real): Real;

 begin
   case
        ComboBox1.ItemIndex of
        0:   result:=a+b;
        1:   result:=a-b;
        2:   result:=a*b;
        3:   result:=a/b;
   end;
end;


{
function TForm1.MyCalculator(var a, b: Real): Real;
 begin
  if ComboBox1.Text='+' then result:=a+b ;
  if ComboBox1.Text='-' then result:=a-b ;
  if ComboBox1.Text='*' then result:=a*b ;
  if ComboBox1.Text='/' then result:=a/b ;
end;
}

 {
 procedure TForm1.Button1Click(Sender: TObject);
var
  a,b:Real;
  result:Real;
begin
  a:=StrToFloat(Edit1.Text);
  b:=StrToFloat(Edit2.Text);
  if ComboBox1.Text='+' then result:=a+b ;
  if ComboBox1.Text='-' then result:=a-b ;
  if ComboBox1.Text='*' then result:=a*b ;
  if ComboBox1.Text='/' then result:=a/b ;
  Label1.Caption:=FloatToStr(result);
end;
 }

end.

 

 

program Project_calculator;

uses
  Forms,
  Unit1_test in 'Unit1_test.pas' {Unit1_test};

{$R *.res}

begin
  Application.Initialize;
  Application.CreateForm(TForm1, Form1);
  Application.Run;
end