Python 如果用户输入正确的运算符，则停止 while 循环

发布于08月06日

I just started learning Python yesterday and one of the programs I'm trying to write is a calculator. This segment of code is where I'm having problems. The while loop is supposed to stop when the user inputs any of the math operators but it still asks for input even when the user enters one the correct characters.

What do I need to do to fix this.

    op = None                                 
    while (op != "-" or op != "+" or op != "*" or op != "/"):
        op = input("Enter operator (-, +, *, /):  ")
    print(op)

推荐答案

  op = None                                 
while op not in ["-","+","*","/"]:
    op = input("Enter operator (-, +, *, /):  ")
print(op)

op = None                                 
while (op != "-" and op != "+" and op != "*" and op != "/"):
    op = input("Enter operator (-, +, *, /):  ")
print(op)

your code isnt working because while "op" might be equal to one of your options, its not equal to all the others, and therefore continues the loop