python位运算版的算术四则运算

#!/usr/bin/python

# -*- coding: utf-8 -*-

class ElementOperator:

    def add(self, num1, num2):

        # 32bits integer max/min

        MAX = 0x7FFFFFFF

        MASK = 0xFFFFFFFF

        ans = num1

        while num2 != 0:

            ans = (num1 ^ num2) & MASK

            num2 = ((num1 & num2) << 1) & MASK

            num1 = ans

        return ans if ans <= MAX else ~(ans ^ MASK)

    def subtract(self, num1, num2):

        mid = self.add(~num2, 1)

        return self.add(num1, mid)

    def is_negative(self, num1, num2):

        return (num1 ^ num2) < 0

    def abs(self, num):

        if num >= 0:

            return num

        else:

            return self.add(~num, 1)

    def multiply(self, num1, num2):

        abs1 = self.abs(num1)

        abs2 = self.abs(num2)

        ans = 0

        while abs2 != 0:

            if abs2 & 1:

                ans = self.add(ans, abs1)

            abs2 = abs2 >> 1

            abs1 = abs1 << 1

        if self.is_negative(num1, num2):

            return self.add(~ans, 1)

        return ans

    def divide(self, num1, num2):

        # exception

        if num2 == 0:

            raise Exception("Divisor is zero.", num2)

        abs1 = self.abs(num1)

        abs2 = self.abs(num2)

        ans = 0

        i = 31

        while i >= 0:

            if (abs1 >> i) >= abs2:

                ans = self.add(ans, 1 << i)

                abs1 = self.subtract(abs1, abs2 << i)

            i = self.subtract(i, 1)

        if self.is_negative(num1, num2):

            return self.add(~ans, 1)

        return ans

if __name__ == '__main__':

    s = ElementOperator()

    print(s.add(5, 2))
巴特西

python位运算版的算术四则运算

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