Nullable With Surprising Result

Question

What prints this program?

static void Main(string[] args)
{
    int? other = null;
    int value = 100 + other ?? 0;
    Console.WriteLine(value);
}

I know I just do not have the language specs in my head. But still it is surprising that it prints 0 instead of 100. Is there a reasonable explanation for this strange behavior?

When I use braces then I get the right result.

static void Main(string[] args)
{
    int? other = null;
    int value = 100 + (other ?? 0);
    Console.WriteLine(value);
}

Answer 1

Currently the expression evaluates as:

(100 + other) ?? 0;

The value of other is null and a number plus null is still null. So the expression outputs 0.

In your second example, you are evaluating the null check first, then adding 100.