方法一：
procedure TFORM1.Edit1KeyPress(Sender: TObject; var Key: Char);
begin
      if not ( Key in ['0'..'9'] ) then
         Key := #0;  //刪掉KEY值，就是不接受非數字的鍵值
end;
方法二：
Try
   Value := StrToInt(Edit1.txt);
except
   MessageBox(GetActiveWindow(),'請輸入數字！','輸入錯誤',MB_OK or MB_ICONERROR);
   Edit1.Setfocus;
   exit;
 end; 

procedure TFORM1.Edit1KeyPress(Sender: TObject; var Key: Char);
begin
  if Not (Key in ['0'..'9', #8] ) then //#8代表后退鍵
    Key := #0;
end;

================================= 有空來瞅瞅我﹗因為我是您的朋友﹐有您真好﹗ ================================

    if not ( (key in ['0'..'9']) or (key=#27) or (key=#08) or (key=#46)
      or (key = #43) or (key=#45) or (key =#13)) then
   begin
   key := #0;
     messagebox(self.Handle ,'請輸入數字' #13
                   ,'waring',mb_iconinformation);
   end;     

引言: 若我要求別人輸入int, 但他輸入字元, 那植個程式也掛了, 有方法可以檢查嗎?