python3中的奇怪错误

Question

我做了一个简单的管理程序，但看起来有一个奇怪的错误。 这是我的代码：

scelta = 0
print("Welcome in the program 'Be in time at home'")
bus = input("Which bus do you need (From university you can choose between bus 5 or 6)? ")
if bus != "5" or bus != "6":
    print("The bus you choose does not go through Universita'")
    program()
else:
    if bus == "5":
        print("You can choose between 2 directions: Viganello and Lamone Cadempino")
        way = input("Make your choice for the direction: ")
    else:
        print("You can choose between 2 directions: Lugano Stazione and Cornaredo")
        way = input("Make your choice for the direction: ")

问题是：即使我按5或6 ，程序也会在错误的if语句中运行（ "The bus you choose does not go..." ）。 这怎么可能？ 看起来很简单。

Answer 1

问题在于您在此行上的if语句条件：

if bus != "5" or bus != "6":

bus将始终不等于"5"或不等于"6" 。 您应该使用and ：

if bus != "5" and bus != "6":

那或者你可以not in使用

if bus not in {"5", "6"}:

如果您要测试许多值，这将特别有用。

Answer 2

如果语句始终为True ：

if bus != "5" or bus != "6"

此时应更换or与and