how to check if item is selected from a comboBox in C#

I'm pretty new here.

I have a form, and want to check if the user filled it in correctly. In the form there's a combo box; how can I build the "if" statement for checking whether the user picked an item from it ?

P.S. Sorry for my bad English, it's not my mother tongue. :)

задан Jimmy 3 October 2019 в 07:21