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Dynamically identify checkboxes (Views: 100)


Problem/Question/Abstract:

My code looks something like this: ... if CheckBox(var).checked = True then ... where (var) is a counter in a for loop. Is the number of checkboxes not known when coding , ie created only at run time?

Answer:

When in design mode, you really should know how many checkboxes are on a given form. When the App is running, use Delphi's Run Time Type Information (RTTI). For a given form, try the following code snippet:

var
  i: Integer
begin
  for i := 0 to ComponentCount - 1 do
    if Components[i] is TCheckBox then
      (Components[i] as TCheckBox).Checked then
    begin
      {... insert your code here ...}
    end;
end;

In addition, the following code is a valid statement in Delphi:

if Components[i] = CheckBox5 then  DoSomething;

Also, each component in Delphi has a Published Property called 'Tag', you can use this to your advantage by setting the Tag to some non-zero number at design time, then using it at runtime, ie:

var
  i: Integer
begin
  for i := 0 to ComponentCount - 1 do
    if Components[i] is TCheckBox then
      with (Components[i] as TCheckBox) do
        case Tag of
          1: if Checked then
              DoSomethingOnBox1;
          2: if Checked then
              DoSomethingOnBox2;
          {... etc ...}
        end;
end;

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