>Hi everybody,
>
>Ok, another beginner question today.
>
>I'm looking at the following code:
>

> if ((this.lsbUsers.SelectedItem != null || this.lsbUsers.Text != string.Empty)
>            && this.LsbRoles.SelectedValue != null)

>
>and although I'm not selecting anything in lsbRoles it's going inside this block of code producing the error.
>
>I see that the SelectedValue is an empty string in the watch window. So, my first guess was that I need to be able to test for both conditions (empty and null).
>
>Googling led me to string.IsEmptyAndNull method, but then I hit this
>http://msmvps.com/blogs/bill/archive/2006/04/04/89234.aspx
>
>So, do you think it's OK to use this method in code or rather use two comparisions instead?
>

I'd personally use string.IsNullOrEmpty() when I need to check for both conditions. The case you linked to definitely looked like a compiler optimization issue - I've not run into any problems in any of my code.