C# IF statements, and doing things very specifically from which is true
===

So, to start, I have seen posts like this: http://stackoverflow.com/questions/6521545/how-to-find-which-condition-is-true-without-using-if-statement

It's not quite what I need, although the idea is pertinent, in that I would like it to be more readable code.

I think Switch is the best bet, but let me explain.

I have this statement:    
    

    if (input == string.Empty || typeComboBox.Text == null)
            {
                MessageBox.Show("Nothing to encrypt!", "Nothing Selected!");            
                return null;

            }

So the idea here is that I used to have this statement broken into two "IF" statements, which isn't a huge deal, but for readability sake, and my on going effort of reducing code, I wanted to combine the statements into one.  

If input is empty, I want the first argument in MessageBox.Show to appear, but not the second.

If typeComboBox.Text is null, I want the second option to appear, but not the first.

If they are both true statements, I want both to appear.

Now, my goal was to have these both done without the use of more than one test or method.  Basically, I mean this: if I can find which condition is true and have the resultant data output within the same statement, that would be ideal. 

I see switches being an option, and I don't understand them very well yet, but I think that would require me to make a decision method based on the outcome of this test, and send that outcome to the switch; which wouldn't be ideal, as I could simply have two if statements and less code.

Is there any way to do this in one statement?  It's not necessary for this specific program, but I want to know for the future.

Thanks!
    