Question

When I execute the following code, I have (for me) some unexpected behaviour.

int i = Int32.MinValue;
i--;
if (i == Int32.MaxValue)
{
    Console.WriteLine("i == Int32.MaxValue");
}
i++;
if (i == Int32.MinValue)
{
    Console.WriteLine("i == Int32.MinValue");
}

Why doesn’t the -1 on Int32.MinValue throw an Exception?

Answer 1

Because of the underflow the values wrap around.

You need to use a checked section if you want overflows/underflows to throw.

The checked keyword is used to explicitly enable overflow checking for integral-type arithmetic operations and conversions.