当然没有人给出正确答案，

num != 0   // num is positive *or* negative!

bool positive = number > 0;
bool negative = number < 0;

    public static bool IsPositive<T>(T value)
        where T : struct, IComparable<T>
    {
        return value.CompareTo(default(T)) > 0;
    }

对于32位有符号整数，例如System。Int32，也就是c#中的int:

bool isNegative = (num & (1 << 31)) != 0;

num < 0 // number is negative

当然没有人给出正确答案，

num != 0   // num is positive *or* negative!