Question

我是python的新手，所以我决定使用函数创建一个基本的计算器应用程序，但是，每当我尝试调用我的一个计算函数时，它都说它是一个未解析的函数引用。我环顾四周，但我不确定发生了什么。

我的代码：

class BasicCalculator:
    # define functions
    def add(x, y):
        """This function adds two numbers"""
        return x + y

    def subtract(x, y):
        """This function subtracts two numbers"""
        return x - y

    def multiply(x, y):
        """This function multiplies two numbers"""
        return x * y

    def divide(x, y):
        """This function divides two numbers"""
        return x / y

    def power(x, y):
        """This function does a power of two numbers"""
        return x ** y


if __name__ == '__main__':

    print("Select an operator")
    print("1. Add")
    print("2. Subtract")
    print("3. Multiply")
    print("4. Divide")
    print("5. Power")

    left = int(input("Enter your left number: "))
    choice = int(input("Select your operator(1, 2, 3, 4): "))
    right = int(input("Select your right number: "))

    if choice == '1':
        #Error is here, it says "Unresolved reference 'add'"
        print(add(left, right))
    else:
        print("Invalid input")

Answer 1

函数add在类BasicCalculator中定义。你需要做BasicCalculator.add()。您也可以在课堂外定义add。

基本上，只需将此行print(add(left, right))更改为print(BasicCalculator.add(left, right))

即可

此外，值得检查其他两个变量（左和右）是否已正确初始化。因此，将if choice == '1':更改为if (choice == '1') and (left is not None) and (right is not None):

Answer 2

你的函数是在我认为的类中定义的 - 尽管你在这里写的缩进并不完全一致。你可以尝试： -

删除第一行＆＃34;类BasicCalculator：＆＃34;
在正确的命名空间中调用您的函数：BasicCalculator.add（左，右）

Answer 3

制作计算器实例

choice = input("Select your operator(1, 2, 3, 4): ") # Not an int
calc = BasicCalculator()
if choice == '1':  # You are comparing strings, not ints
    print(calc.add(left, right))

Answer 4

您的代码有4个问题需要修复：

1st：您需要添加self作为BasicCalculator类中所有方法的第一个参数，self是对当前实例的引用班级：

class BasicCalculator:
    # define functions
    def add(self, x, y):  # self must be the first argument
        """This function adds two numbers"""
        return x + y

    # ...

第二名：您需要实例化您的课程：

calculator = BasicCalculator()

第3名：按照以下方式调用您的函数：

calculator.add(left, right)

第4名：您需要修正if声明：

if choice == 1:  # not '1', because choice is an integer (choice = int(input("...")))

所有在一起：您的代码现在应如下所示：

class BasicCalculator:
    # define functions
    def add(self, x, y):
        """This function adds two numbers"""
        return x + y

    def subtract(self, x, y):
        """This function subtracts two numbers"""
        return x - y

    def multiply(self, x, y):
        """This function multiplies two numbers"""
        return x * y

    def divide(self, x, y):
        """This function divides two numbers"""
        return x / y

    def power(self, x, y):
        """This function does a power of two numbers"""
        return x ** y


if __name__ == '__main__':

    print("Select an operator")
    print("1. Add")
    print("2. Subtract")
    print("3. Multiply")
    print("4. Divide")
    print("5. Power")

    left = int(input("Enter your left number: "))
    choice = int(input("Select your operator(1, 2, 3, 4): "))
    right = int(input("Select your right number: "))

    calculator = BasicCalculator()

    if choice == 1:
        print(calculator.add(left, right))
    else:
        print("Invalid input")

PyCharm中未解决的引用错误

4 个答案: