Question

I hope this hasn’t been asked before.

I have a nullable boolean called boolIsAllowed and a if condition like so:

if(boolIsAllowed.HasValue && boolIsAllowed.Value)
{
 //do something
}

My question is this good code or would I be better separating it into a nested if statement? Will the second condition get checked if boolIsAllowed.HasValue is equal to false and then throw an exception?

I hope this question isn’t too stupid.

Thanks in advance.

Answer 1

It’s fine as is. The second condition won’t be checked if HasValue is false, so it won’t throw an exception. It’s like this sort of thing:

string name = ...;
if (name != null && name.Length > 5)

Again, that’s fine – you won’t get a NullReferenceException if name is null, because && is short-circuiting.

Likewise the || operator is short-circuiting, but in the reverse way – there, if the left hand operand is true, the overall expression evaluates to true without checking the right hand operand. For example:

// Treat null as if it were an empty string
if (name == null || name.Length == 0)

EDIT: As noted in comments, this only applies to && and || – it doesn’t apply to & and |, which always evaluate both operands.