Question

This will throw a null reference exception when InnerException is null.

String s = " inner exception: " + e.InnerException == null ? "None" : e.InnerException.Message;

but this won’t:

String s = " inner exception: " + (e.InnerException == null ? "None" : e.InnerException.Message);

Both of the above build fine. I can’t figure out what the former is trying to do that would cause it to evaluate e.InnerException.Message. Why aren’t they equivalent?

Answer 1

This is because your first statement is evaluating " inner exception: " + e.InnerException == null to be true or false. It’s all about operator precedence, which is why the second works just fine due to the parenthesis (( and )).

See this reference for Operator Precedence. The + operator is evaluated before the equality == operator.