python - 重复输入

Question

我想这样编程，所以在输入 num1，num2 和操作时，如果用户没有以适当的类型提供输入，它会再次要求用户输入。

operation=(input('1.add\n2.subtract\n3.multiply\n4.divide'))
num1 =int(input("Enter first number: "))
num2 = int(input("Enter second number: "))

if operation == "add" or operation == '1' :
   print(num1,"+",num2,"=", (num1+num2))
elif operation =="subtract" or operation == '2':
   print(num1,"-",num2,"=", (num1-num2))
elif operation =="multiply" or operation == '3':
   print(num1,"*",num2,"=", (num1*num2))
elif operation =="divide" or operation == '4':
   print(num1,"/",num2,"=", (num1/num2))

标签： python

Answer 1

您可以使用in关键字。

前任：

>>> "1" in ["1","add"]
True
>>> "add" in ["1","add"]
True

修改代码如：

 operation=(input('1.add\n2.subtract\n3.multiply\n4.divide'))

    num1 = int(input("Enter first number: "))
    num2 = int(input("Enter second number: "))

    if operation in ["1","add"] :
       print(num1,"+",num2,"=", (num1+num2))
    elif operationi in ["2", "subtract"]:
       print(num1,"-",num2,"=", (num1-num2))
    elif operation in ["3", "multiply"]:
       print(num1,"*",num2,"=", (num1*num2))
    elif operation in ["4", "divide"]:
       print(num1,"/",num2,"=", (num1/num2))
    else:
        print("Invalid Input")