Python:if not true函数没有按应有的方式运行[重复]

Question

如果用户没有输入乘法、加法等，则应打印字符串。但是，如果键入其中一个单词，它仍会打印此字符串。我刚开始学习python；很抱歉，这是一个如此基本的问题！

print ("Multiplication, Addition, Subtraction or Division?")
type = str(input("Your choice:"))
if type != "multiplication" or "addition" or "subtraction" or "division":
    print("YOU DID NOT ENTER ONE OF THE ABOVE OPTIONS.\nTRY AGAIN!")
num1 = int(input("Enter your 1st number:"))

Answer 1

问题在于你的if语句。当您测试某个值是否为多个选项之一时，可以使用中的关键字，如[“hello”，“test”，“123”]==true中的“test”。

print ("Multiplication, Addition, Subtraction or Division?")
type = str(input("Your choice:"))

if type not in ["multiplication", "addition", "subtraction", "division"]:
    print("YOU DID NOT ENTER ONE OF THE ABOVE OPTIONS.")
    print("TRY AGAIN!")

Answer 2

print ("Multiplication, Addition, Subtraction or Division?")
choice = input("Your choice:")
if choice.lower() not in ("multiplication", "addition", "subtraction", "division"):
    print("YOU DID NOT ENTER ONE OF THE ABOVE OPTIONS.\nTRY AGAIN!")
num1 = int(input("Enter your 1st number:"))

此外type是内置的全局名称。通过使用这个名字，你隐藏了它。