Python-为什么我的 elif 语句没有在考虑负数的递归乘法中得到评估 [英] Python-Why aren't my elif statements not getting evaluated in this recursive multiplication which takes into account negative numbers

问题描述

我在 python 中查找了一些 2 个数字的递归乘法，但没有一个考虑到负数的可能性，或者如果他们考虑了，他们就没有解释整个步骤.

Hi I have looked up a few recursive multiplication of 2 numbers in python, but none of them take into account the possibility of negative numbers or if they do they don't explain the entire steps.

我已经编写了以下程序，但出现错误，有人可以告诉我它有什么问题吗?

I have coded the following the program but I am getting an error, can someone please let me know what is wrong with it?

def mult(a,b):
    if a==0 | b==0:
        return 0
    elif a==1:
        return b
    elif a > 0 & b >0:
        return b + mult(a-1,b)
    elif  a < 0 & b > 0:
        return - b + mult(a+1,b))
    elif a > 0 & b < 0:
        return - b + mult(a-1, b))
    else:
        return -b + mult(a+1, b)

print(mult(-4,5))

推荐答案

| 和 & 是按位运算符，不是逻辑运算符，它们的 (相对)高优先级 意味着 a >0 &b >0 被解析为 a >(0 & b) >0，这不是你想要的.使用 or 和 and 代替.

| and & are bitwise operators, not logical operators, and their (relatively) high precedence means that a > 0 & b >0 is parsed as a > (0 & b) > 0, which is not what you want. Use or and and instead.

这篇关于Python-为什么我的 elif 语句没有在考虑负数的递归乘法中得到评估的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！