WPF, count number of empty textbox and ComboBox

I have a C# WPF application with 400+ textbox and combo box. I need to count number of empty or null textbox and combo box. i have below code to count. but the problem is i have 400+ tests. It doesnt look like "smart" code if I follow the same way to count 400+ textboxes. Is there a better way to handle this case? Any help are much appreciated

 

 

int i = 0;

if (!String.IsEmptyorNull(txtBox1.Text))

{

i++;

}

else

{

if (!String.IsNullOrEmpty(txtBox2.Text))

i++;

}

txtTotal = i.ToString();