Keep track clicks on button in another form

I'm working on a project which has 4 combo boxes.
Each of them has a drop down list of numbers from 0 to 9.

How do I validate if each combo box is selected with one number when I click on a button?

Is validating a checkbox the same way as validating combo box?

Thank you.

If something in the combo is selected, it will be in its text property so you could check to see whether that is empty or not.

Checkboxes have a "Checked" property

vb.net Code:

If CheckBox1.Checked = True Then
      MessageBox.Show("checked")
Else
      MessageBox.Show("unchecked")
End If

On form load, you set the combobox.selectedIndex property of all 4 comboboxes to -1.
In your button click event handler, you read the combobox.selectedindex of the 4 above mentioned comboboxes, and if any of them is < 0, that combobox is not yet selected by the user.

Quote:

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Originally Posted by stanav

On form load, you set the combobox.selectedIndex property of all 4 comboboxes to -1.
In your button click event handler, you read the combobox.selectedindex of the 4 above mentioned comboboxes, and if any of them is < 0, that combobox is not yet selected by the user.

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Thanks for your reply.

I have another question: For a lottery program, I like to keep track how many the user has played the game.
The main form where the user needs to click on a button called "PLAY" to proceed the game.
I have another new form that will keep track numbers of game he/she has played (I'd like to show the numbers of game in a label).