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}

//自定义的 Pos 函数
function MyPos(c: Char; const str: string): Integer;
var
  i: Integer;
begin
  Result := 0;
  for i := 1 to Length(str) do
    if c = str[i] then begin Result := i; Exit end;
end;

{对比测试}
procedure TForm1.Button1Click(Sender: TObject);
var
  s: string;
  c: Char;
  i: Integer;
  n: Cardinal;
begin
  s := 'abcdefghijklmnopqrstuvwxyz';
  Randomize;
  c := Chr(Random(26) + 97); {随机一个 a..z 的字符}

  {用 Pos 函数}
  n := GetTickCount;
  for i := 1 to 1000000 do Pos(c,s);
  n := GetTickCount - n;
  Text := IntToStr(n) + ' - ';

  {用自定义的 MyPos 函数}
  n := GetTickCount;
  for i := 1 to 1000000 do MyPos(c,s);
  n := GetTickCount - n;
  Text := Text + IntToStr(n);

  Button1.Caption := 'Pos 与 MyPos 速度测试';
end;

end.