如何在 Delphi 中使用复选框？

Question

Right now, I have the code:

begin
If odd(GetAsyncKeyState(VK_snapshot)) then
If CheckBox1.Checked then
begin

And then it continues on with the rest of the code. Is that the correct way of doing that, or am I doing it wrong?

Answer 1

What you suggest is a perfectly legal way to determine if a checkbox is checked. The code doing so might look like

if checkBox.Checked then begin
    //do whatever needed for checked checkbox
end

or like this

if checkBox.Checked then begin
    //do whatever needed for checked checkbox
end else begin
    //do whatever needed for unchecked checkbox
end

Just remember that the value you obtained from Checked property corresponds to the checkbox's state at the moment when you obtained the value.

Answer 2

if DT.FieldByName('name_of_checkbox').AsBoolean=True then begin ..... end;
// In this case dt is TADOquery that you had used in your program.

Answer 3

since you are using 2 if-statements, you might also combine them into one:

if odd(GetAsyncKeyState(VK_snapshot)) and CheckBox1.Checked then
begin
  ...
  ...
end;

The second part of the if-statement (checkbox1.Checked) will only be evaluated if the first one evaluates to True. (Since Delphi uses Short-circuit evaluation )