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  • Delphi 中的 IfThen 函数

    问题来源: http://www.cnblogs.com/del/archive/2008/11/14/1120015.html#1370413

    StrUtils 单元和 Math 单元 分别有一个 IfThen 函数(注意参数是数字还是字符串), 举例:

    StrUtils 单元和 Math 单元 分别有一个 IfThen 函数, 举例:
    unit Unit1;
     
    interface
     
    uses
      Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
      Dialogs, StdCtrls;
     
    type
      TForm1 = class(TForm)
        Button1: TButton;
        Button2: TButton;
        procedure Button1Click(Sender: TObject);
        procedure Button2Click(Sender: TObject);
      end;
     
    var
      Form1: TForm1;
     
    implementation
     
    {$R *.dfm}
     
    uses StrUtils, Math;
     
    procedure TForm1.Button1Click(Sender: TObject);
    var
      a: Integer;
      str: string;
    begin
      a := 1;
      str := StrUtils.IfThen(a > 0, 'aaa', 'bbb');
      ShowMessage(str); {aaa}
     
      a := -1;
      str := StrUtils.IfThen(a > 0, 'aaa', 'bbb');
      ShowMessage(str); {bbb}
     
      a := 1;
      str := StrUtils.IfThen(a > 0, 'aaa');
      ShowMessage(str); {aaa}
     
      a := -1;
      str := StrUtils.IfThen(a > 0, 'aaa');
      ShowMessage(str); {}
    end;
     
    procedure TForm1.Button2Click(Sender: TObject);
    var
      str: string;
      num: Integer;
    begin
      str := '万一';
      num := Math.IfThen(str <> '', 99, 11);
      ShowMessage(IntToStr(num)); {99}
     
      str := '';
      num := Math.IfThen(str <> '', 99, 11);
      ShowMessage(IntToStr(num)); {11}
     
      str := '万一';
      num := Math.IfThen(str <> '', 99);
      ShowMessage(IntToStr(num)); {99}
     
      str := '';
      num := Math.IfThen(str <> '', 99);
      ShowMessage(IntToStr(num)); {0}
    end;
     
    end.
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  • 原文地址:https://www.cnblogs.com/westsoft/p/10360387.html
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