if Assigned(from1) then // from1窗体存在procedure TForm1.FormDestroy(Sender: TObject); begin form1 := nil; end;
form1为自动创建。for i:=0 to Application.ComponentCount-1 do begin if Application.Components[i] = form1 then .... end;
以前我判断控件是否存: var TempMItem: TMenuItem; i: Integer; begin try TempMItem := FindComponent('MainSourceMItem') as TMenuItem; if TempMItem <> nil then ...... ...... 找是否存在名字为:MainSourceMItem的菜单项
begin
form1 := nil;
end;
begin
if Application.Components[i] = form1 then
....
end;
var
TempMItem: TMenuItem;
i: Integer;
begin
try
TempMItem := FindComponent('MainSourceMItem') as TMenuItem;
if TempMItem <> nil then
......
......
找是否存在名字为:MainSourceMItem的菜单项