在 case 语句中使用字符串

unit Unit1;interfaceuses  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,  Dialogs, StdCtrls, ExtCtrls;type  TForm1 = class(TForm)    RadioGroup1: TRadioGroup;    Button1: TButton;    Button2: TButton;    Button3: TButton;    Button4: TButton;    Button5: TButton;    Button6: TButton;    procedure FormCreate(Sender: TObject);    procedure Button1Click(Sender: TObject);    procedure Button2Click(Sender: TObject);    procedure Button3Click(Sender: TObject);    procedure Button4Click(Sender: TObject);    procedure Button5Click(Sender: TObject);    procedure Button6Click(Sender: TObject);  end;var  Form1: TForm1;implementation{$R *.dfm}uses TypInfo; {操作枚举用}{初始化一个单选组, 用于测试}procedure TForm1.FormCreate(Sender: TObject);begin  RadioGroup1.Items.CommaText := ‘a,bb,ccc,dddd‘;  RadioGroup1.ItemIndex := 0;end;{这是 case 语句比较常规的用法}procedure TForm1.Button1Click(Sender: TObject);begin  case RadioGroup1.ItemIndex of    0: Color := clRed;    1: Color := clYellow;    2: Color := clLime;    3: Color := clBlue;  end;end;{方法一: 假如要 case 的字符串的长度不同}procedure TForm1.Button2Click(Sender: TObject);var  str: string;begin  str := RadioGroup1.Items[RadioGroup1.ItemIndex];  case Length(str) of    1 : Color := clRed;    2 : Color := clYellow;    3 : Color := clLime;    4 : Color := clBlue;  end;end;{方法二: 假如要 case 的字符串的第一个字母不同, case 是支持字符的}procedure TForm1.Button3Click(Sender: TObject);var  str: string;begin  str := RadioGroup1.Items[RadioGroup1.ItemIndex];  case str[1] of    ‘a‘: Color := clRed;    ‘b‘: Color := clYellow;    ‘c‘: Color := clLime;    ‘d‘: Color := clBlue;  end;end;{方法三: 借用 TStringList}procedure TForm1.Button4Click(Sender: TObject);var  List: TStringList;  str: string;begin  List := TStringList.Create;  List.Text := RadioGroup1.Items.Text;  str := RadioGroup1.Items[RadioGroup1.ItemIndex];  case List.IndexOf(str) of    0: Color := clRed;    1: Color := clYellow;    2: Color := clLime;    3: Color := clBlue;  end;  List.Free;end;{方法四: 借用枚举}type  TMyEnum = (a, bb, ccc, dddd);procedure TForm1.Button5Click(Sender: TObject);var  MyEnum: TMyEnum;  str: String;begin  str := RadioGroup1.Items[RadioGroup1.ItemIndex];  MyEnum := TMyEnum(GetEnumvalue(TypeInfo(TMyEnum), str));  case MyEnum of    a    : Color := clRed;    bb   : Color := clYellow;    ccc  : Color := clLime;    dddd : Color := clBlue;  end;end;{方法五: 利用对比字符串返回的整数, 这种方法并不太可靠, 但在某种情况下会更灵活}procedure TForm1.Button6Click(Sender: TObject);var  str: string;begin  str := RadioGroup1.Items[RadioGroup1.ItemIndex];  case CompareStr(str, ‘a‘) of    0: Color := clRed;    1: Color := clYellow;    2: Color := clLime;    3: Color := clBlue;  end;end;end.

object Form1: TForm1  Left = 0  Top = 0  Caption = ‘Form1‘  ClientHeight = 111  ClientWidth = 265  Color = clBtnFace  Font.Charset = DEFAULT_CHARSET  Font.Color = clWindowText  Font.Height = -11  Font.Name = ‘Tahoma‘  Font.Style = []  OldCreateOrder = False  Position = poDesktopCenter  OnCreate = FormCreate  PixelsPerInch = 96  TextHeight = 13  object Button1: TButton    Left = 16    Top = 15    Width = 75    Height = 25    Caption = ‘Button1‘    TabOrder = 0    OnClick = Button1Click  end  object Button2: TButton    Left = 97    Top = 15    Width = 75    Height = 25    Caption = ‘Button2‘    TabOrder = 1    OnClick = Button2Click  end  object Button3: TButton    Left = 16    Top = 46    Width = 75    Height = 25    Caption = ‘Button3‘    TabOrder = 2    OnClick = Button3Click  end  object RadioGroup1: TRadioGroup    Left = 178    Top = 8    Width = 80    Height = 94    Caption = ‘RadioGroup1‘    TabOrder = 3  end  object Button4: TButton    Left = 97    Top = 46    Width = 75    Height = 25    Caption = ‘Button4‘    TabOrder = 4    OnClick = Button4Click  end  object Button5: TButton    Left = 16    Top = 77    Width = 75    Height = 25    Caption = ‘Button5‘    TabOrder = 5    OnClick = Button5Click  end  object Button6: TButton    Left = 97    Top = 77    Width = 75    Height = 25    Caption = ‘Button6‘    TabOrder = 6    OnClick = Button6Click  endend