如何知道表单上的某一控件是否存在?如button,edit等

Question

use findcomponentorfor i:=0 to componentcount-1 do
  if  components[i].name.... 

Answer 1

可以给这些控件的tag赋一个值
然后利用formX.Controls[]进行判断

Answer 2

for i:=0 to ComponentCount-1 do begin
  if Components[i] is TDBcomboBox then
    with Components[i] as TDBcomboBox do ...
  if Components[i] is TDBedit then
    with Components[i] as TDBedit do ...
  if Components[i] is TDBmemo then
    with Components[i] as TDBmemo do ...
  ...
end;

Answer 3

for i:=0 to ComponentCount-1 do 
begin
  if Components[i] is TButton then  
end;
=================================
for i:=0 to Panel1.ControlCount-1 do
begin
     if Panel1.Controls[i] is TButton then
          ShowMessage((Panel1.Controls[i] as Tbutton).Caption);
end;