Question

我正在尝试用python创建我的第一个程序。我为两个数字（num1和num2）制作了一系列if语句。我所有的代码都适用于加，乘和除运算符，但是当我使用减法运算符时，要么没有收到消息，要么输出“无效运算符”。我确定我今天刚开始学习python时，就已经做了一些简单的错误，但是我将不胜感激。谢谢。

num1= float(input("enter first number:"))
operator = (input("enter operator:"))
num2= float(input("enter second number:"))
if operator== ("add" or "+" "sum"or "summation"):
    print(num1+num2)
elif operator== ("multiply" or "multiplication" or"*"):
    print(num1*num2)
elif operator== ("divide" or "division" or "/"):
    print(num1/num2)
elif operator== ("minus" or "subtract" or "-"):
    print(num1-num2)
else:
    print("Invalid Operator")

输出：

C:\Users\clubj\PycharmProjects\untitled9\venv\Scripts\python.exe "C:/Users/clubj/PycharmProjects/untitled9/better calculator.py"
enter first number:32
enter operator:-
enter second number:6
Invalid Operator

以退出代码0结束的过程

Answer 1

替换所有or，然后创建一个元组。您的代码只有在您编写时才会

if (operator== "add") or (operator=="+") or (operator=="sum") or (operator =="summation"):

代替

operator== ("add" or "+" or "sum" or "summation"):

num1= float(input("enter first number:"))
operator = (input("enter operator:"))
num2= float(input("enter second number:"))
print(operator)
if operator in ("add", "+", "sum", "summation"):
    print(num1+num2)
elif operator in ("multiply", "multiplication", "*"):
    print(num1*num2)
elif operator in ("divide", "division", "/"):
    print(num1/num2)
elif operator in ("minus", "subtract", "-"):
    print(num1-num2)
else:
    print("Invalid Operator")

Answer 2

您也可以尝试python builtin function eval()。评估函数通常用于需要评估mathematical表达式的情况或应用程序中。同样，如果用户要将string评估为code，则可以使用eval函数，因为eval函数评估字符串表达式并返回整数作为结果。

num1= input("enter first number:")
operator = input("enter operator:")
num2= input("enter second number:")
if operator in ["+", '-', '/', '*', '//', '%']:
    print(eval(num1+ operator+ num2))
else:
    print("Invalid operator")

基本计算器的“减”功能不起作用

2 个答案: