调用和打印 class 时出现问题

Question

我正在做一个家庭作业，其中我们正在创建一个 class 用于程序中，用于单独或一次进行所有计算的基本数学计算。所以加、减、乘、除或全部四项。

我认为大部分代码都不错，但在用户输入数字并选择计算方法后，我无法将其打印出来。我试过 print(Week7.addNum)、print(Week7.addNum())、print(Week7.addnum(numOne, numTwo))。我收到各种错误或什么都没有。随着 print(Week7.addnum) 我得到了。我一直在研究添加功能，并想知道我是否可以让它工作，其余的也可以效仿。

class Week7:

    def __init__(self, numOne, numTwo):
        self.numOne = numOne
        self.numTwo = numTwo

    def addNum(self):
        return (self.numOne + self.numTwo)

    def subtNum(self):
        return (self.numOne - self.numTwo)

    def multNum(self):
        return (self.numOne * self.numTwo)

    def divNum(self):
        if self.numTwo !=0:
            return (self.numOne / self.numTwo)
        else:
            return print('You can not divde by 0')

    def allNum(self):
        return (self.numOne + self.numTwo, self.numOne - self.numTwo,     self.numOne * self.numTwo, self.numOne / self.numTwo )



numOne=int(input("Enter first number: "))
numTwo=int(input("Enter second number: "))
functions = [ "1) Add two numbers",
          "2) Mult two numbers",
          "3) Divide two numbers",
          "4) Subtract two numbers",
          "5) All in one: Perform all math Operations",
          "6) End Program" 
        ]
for x in functions:                  
      print( x )
print()


which_Function = int(input("Please select what operation you would like to perform: ") )



if which_Function == 1:
     print(Week7.addNum)

elif which_Function == 2:
     Week7.subtNum(self)

elif which_Function == 3:
     Week7.multNum(self)

elif which_Function == 4:
     Week7.divNum(self)

elif which_Function == 5:
     Week7.allNum(self)

elif which_Function == 6:
     exit

我认为除了问题的实际打印外，一切正常。我想以“1 + 2 = 3”为例。我知道我需要在打印输出中放置“+”和“=”，但我完全可以弄清楚在哪里打印。提前致谢。戴夫

Answer 1

您需要创建 class 的实例。尝试类似的东西：

instance = Week7(numOne, numTwo)

if which_Function == 1:
   print(instance.addNum())

elif which_Function == 2:
   print(instance.subtNum())

...

我命名为 instance 的对象将作为 self 传递给方法，因为这是您调用它们的对象。当您查找 instance.addNum 时，您会得到一个 "bound method" 对象，它会自动为您传递参数。

Answer 2

编辑后的代码，应该可以工作：

class Week7:

    def __init__(self, numOne, numTwo):
        self.numOne = numOne
        self.numTwo = numTwo

    def addNum(self):
        return (self.numOne + self.numTwo)

    def subtNum(self):
        return (self.numOne - self.numTwo)

    def multNum(self):
        return (self.numOne * self.numTwo)

    def divNum(self):
        if self.numTwo !=0:
            return (self.numOne / self.numTwo)
        else:
            return print('You can not divde by 0')

    def allNum(self):
        return (self.numOne + self.numTwo, self.numOne - self.numTwo,     self.numOne * self.numTwo, self.numOne / self.numTwo )



numOne=int(input("Enter first number: "))
numTwo=int(input("Enter second number: "))

w7 = Week7(numOne, numTwo)

functions = [ "1) Add two numbers",
          "2) Mult two numbers",
          "3) Divide two numbers",
          "4) Subtract two numbers",
          "5) All in one: Perform all math Operations",
          "6) End Program" 
        ]
for x in functions:                  
      print( x )
print()


which_Function = int(input("Please select what operation you would like to perform: ") )



if which_Function == 1:
     print(w7.addNum())

elif which_Function == 2:
     print(w7.multNum())

elif which_Function == 3:
     print(w7.divNum())

elif which_Function == 4:
     print(w7.subtNum())

elif which_Function == 5:
     print(w7.allNum())

elif which_Function == 6:
     exit()

更改说明：

w7 = Week7(numOne, numTwo) 创建 Week7 对象的实例
print(w7.addNum()) 调用函数并打印输出。
--ditto--mult-----等

我也更改了顺序，因为它与显示的内容不相关。

调用和打印 class 时出现问题

Having a problem with calling and printing out of a class

class

calling-convention

python-3.x