分数代码无法计算具有相同值的分数的差异

Question

我创建了一个包含 +、-、*、/ 的分数计算器。除了两个值相等的减法条件外，我的所有函数都可以正常工作。我相信这与我添加的 simplify(gcd) 函数有关，但不确定问题出在哪里。下面是我只保留了用于确定问题优先级的减法函数的代码：

Class Fraction:
     def __init__(self, num, denom) -> None:  

        self.num = int(num / simplify(abs(num), abs(denom)))
        self.denom = int(denom / simplify(abs(num), abs(denom)))
        if self.denom < 0:
            self.denom = abs(self.denom)
            self.num = -1*self.num
        elif self.denom == 0:
            raise ZeroDivisionError("cansnot divide by zero")


    def __sub__(self, other: "Fraction") -> "Fraction":  

    
        n: int = self.num * other.denom - self.denom * other.num
        d: int = self.denom * other.denom
        new = Fraction(n, d)
        return (new)
 
    def __str__(self) -> str:  

    
        if self.denom == 1:
            return str(self.num)
        else:
            return(f"{self.num}/{self.denom}")


def simplify(num, denom):

    while num != denom:
        if num > denom:
            num = num - denom
        else:
            denom = denom - num
    return num


def get_fraction() -> Fraction:

"""Convert numerator and denominator to integer values"""

while True:
    num: str = input("Enter the numerator")
    denom: str = input("Enter the denominator")
    try:
        a = int(num)
        b = int(denom)
        return Fraction(a, b)
    except ValueError:
        print("Enter valid numerator and denominator")

def compute(f1: Fraction, operator: str, f2: Fraction) -> None:

okay = True
if operator == '-':
    result = f1.__sub__(f2)
else:
    print(operator, " is an unrecognized operator")
    okay = False

if okay == True:
 
    print(f"{f1} {operator} {f2} = {result}")

def main() -> None:

"""Main menu"""

print("Welcome to the Fraction Calculator! ")
while True:
    print('Press Q to quit or any other key to start')
    z = input("Start or Quit?")
    if z == 'Q' or z == 'q':
        exit()
    else:
        f1: Fraction = get_fraction()
        operator: str = input("Operation (+, -, *, / , = , < , > , <= , >= , != ): ")
        f2: Fraction = get_fraction()

        try:
            compute(f1, operator, f2)
        except ZeroDivisionError as e:
            print(e)


if __name__ == '__main__':
    
    main()

下面是此代码的输出，其中两个分数都是 4/5，它只是给我一个空白输出。

Welcome to the Fraction Calculator!
Press Q to quit or any other key to start
Start or Quit? s
Enter the numerator 4
Enter the denominator 5
Operation (+, -, *, / , = , < , > , <= , >= , != ): -
Enter the numerator 4 
Enter the denominator 5

所有其他值都适用于子函数，除非值相等。

Answer 1

您的简化方法是 gcd 的较慢版本，当 num 为零时将陷入无限循环。

您可以将其替换为：

 from math import gcd
 def simplify(num, denom):
     return gcd(num,denom) if denom else 1

如果您不想导入数学，您可以使用比您当前在 simplify 中使用的减法形式更快的算法编写您自己的 gcd() 函数版本：

def gcd(a,b):
    while b != 0: a,b = b,a%b
    return abs(a)

或者，您可以将 simplify() 的代码替换为两个组件的实际简化，一步将标志置于顶部：

 def simplify(num, denom):
     g = gcd(num,denom) if denom else 1
     s = -1 if (num<0) != (denom<0) else 1
     return int(abs(num) // g * s), int(abs(denom) // g)

并在构造函数中像这样使用它：

 self.num,self.denom = simplify(num,denom)

如果您使用 Decimal()（来自 decimal 模块）而不是 int() 转换字符串输入，这个改进的 simplify() 可以做更酷的事情，例如弄清楚：

simplify(-8.5,12.5)   # is (-17, 25)

例如：

from decimal import Decimal
f = input("enter a fraction as a/b or a decimal value: ")
num,denom,*_ = map(Decimal,(*f.split("/"),1))
print(simplify(num,denom))

enter a fraction as a/b or a decimal value: 0.68
(17, 25)

分数代码无法计算具有相同值的分数的差异

Fractions code not able to calculate difference for fractions with same values

python

class

function

fractions

python-3.x