What does base.OnStartup(e) do?

Question

I see that many people use "base.OnStartup(e)" inside of App.xaml.cs like this:

protected override void OnStartup(StartupEventArgs e)
{
    base.OnStartup(e);

    MainWindow app = new MainWindow();
    app.Show();
}

Is there a need for it? What is the purpose for it?

Answer 1

It allows any base class logic to run; just like any other usage of base.

Its probably not strictly necessary; but calling a base class's implementation when overriding virtual methods is considered a best practice (unless you actively want to suppress the base behavior).