C#ulong允许溢出/下溢

Question

ulong big = 1000000;    //Perfectly legal

ulong negative = -1;    //"Constant value "-1" cannot be converted to a ulong" Makes sense


//Attempt to sneak around the -1 as a constant compile-time error
int negativeInt = -1;
ulong negativeUlongFail = negativeInt;    //"Cannot implicitly convert 'int' to 'ulong'.
                                 //An explicit conversion exists (are you missing a cast?)"
//So I add casting
ulong negativeUlong = (ulong)negativeInt;    //But this yields 18446744073709551615

//Try and get a negative number indirectly
ulong number = 0;
number = number - 10;  //now number is 18446744073709551615 but no underflow error

Answer 1

如果希望引发下溢（或溢出）异常，请尝试以下操作：-

checked
{
    ulong number = 0;
    number = number - 10;
}

默认情况下，异常被吞掉（它在未选中状态下运行）。

见官方文件