The string does not concatenate as I would expect

Question

I just do not understand why the following statement does not evaluate as I expected.

With UserFirstNameset to "Joe" and the UserLastNamevalue "Plumber", SpeakerNameonly "Joe" gets.

spr.SpeakerName = presenterRec.UserFirstName ?? "" + " " + 
    presenterRec.UserLastName ?? "";

Thoughts?

+3

Peter Kellner Jan 13 '14 at 10:55

2 answers

Steve · Answer 1 · 2014-01-13T22:56:52+0000

Because, if presenterRec.UserFirstNameit is not null, you get that value, and the evaluation of your expression stops there.

In other words, you have a problem with the order of operations. Try the following:

spr.SpeakerName = (presenterRec.UserFirstName ?? "") 
                  + " " +  
                  (presenterRec.UserLastName ?? "");

CompuChip · Answer 2 · 2014-01-13T23:00:04+0000

A zero-coalescing operator has a rather low priority, as described in MSDN .

The solution, as already mentioned, adds parentheses

(presenterRec.UserFirstName ?? "") 
            + " " + 
            (presenterRec.UserLastName ?? "")

.NET ,

presenterRec.UserFirstName + " " + presenterRec.UserLastName

.