def gcd(n, d):
if n==0 or d==0:
return 1
while(n != d):
if(n > d):
n = n - d
else:
d = d - n
return n
class Fraction:
def __init__(self, n, d):
self.num = int(n / gcd(abs(n), abs(d)))
self.denom = int(d / gcd(abs(n), abs(d)))
if self.denom < 0:
self.denom = abs(self.denom)
self.num = -1 * self.num
elif self.denom == 0:
raise ZeroDivisionError
def __str__(self):
if type(self) is tuple:
if self[1] < 0:
return '%s/%s' %(self[0], -1*self[1])
else:
return '%s/%s' %(self[0], self[1])
elif self.denom == 1:
return str(self.num)
else:
return '%s/%s' %(self.num, self.denom)
def __add__(self, other):
return self.num*other.denom + self.denom*other.num, self.denom*other.denom
def __sub__(self, other):
return self.num*other.denom - self.denom*other.num, self.denom*other.denom
def __mul__(self, other):
return self.num*other.num, self.denom*other.denom
def __div__(self, other):
return self.num*other.denom, self.denom*other.num
def __eq__(self, other):
if self.num == other.num and self.denom == other.denom:
return "Equal"
else:
return "Not Equal"
f1 = Fraction(2, 4)
f2 = Fraction(4, 20)
add = Fraction.__add__(f1, f2)
sub = Fraction.__sub__(f1, f2)
eq = Fraction.__eq__(f1, f2)
mul = Fraction.__mul__(f1, f2)
div = Fraction.__div__(f1, f2)
print("Fraction one: "+str(Fraction.__str__(f1))+"\n"+"Second Fraction: "+str(Fraction.__str__(f2))+"\n"+"Add: "+str(Fraction.__str__(add))+"\n"+"Subtract: "+str(Fraction.__str__(sub))+"\n"+"Multiply: "+str(Fraction.__str__(mul))+"\n"+"Divide: "+str(Fraction.__str__(div))+Fraction.__str__(eq))
所以我的作业要求我做一个分数函数，但是我的代码不断出现以下错误，我不确定为什么：
Traceback (most recent call last):
File "G:\Workshops\Week9.py", line 57, in <module>
print("Fraction one: "+str(Fraction.__str__(f1))+"\n"+"Second Fraction: "+str(Fraction.__str__(f2))+"\n"+"Add: "+str(Fraction.__str__(add))+"\n"+"Subtract: "+str(Fraction.__str__(sub))+"\n"+"Multiply: "+str(Fraction.__str__(mul))+"\n"+"Divide: "+str(Fraction.__str__(div))+Fraction.__str__(eq))
File "G:\Workshops\Week9.py", line 26, in __str__
elif self.denom == 1:
AttributeError: 'str' object has no attribute 'denom'
他们希望您使用__来定义方法，但这不是您use方法的方式。
__add__例如是+。而不是写
add = Fraction.__add__(f1, f2)
只需写
add = f1 + f2
[所有其他数学运算符以及__str__（内置str内置函数也是如此）。
您的主要问题是eq是字符串*，并且您在编写时将其传递给__str__方法
Fraction.__str__(eq)
这意味着self内的__str__是string，而不是Fraction，这意味着self.denom正试图获得denom字符串self的]属性。
因为您将eq作为字符串，所以只需更改
Fraction.__str__(eq)
至
eq
*不过，__eq__不应返回字符串。这不是不允许的，但是它很奇怪并且使__eq__不太有用。刚有
def __eq__(self, other):
return self.num == other.num and self.denom == other.denom
然后将上面提到的修复程序更改为
str(eq)