题解 | #禁止重复注册#

current_users = ["Niuniu", "Niumei", "GURR", "LOLO"]
new_users = ["GurR", "Niu Ke Le", "LoLo", "Tuo Rui Chi"]
for i in new_users:
    for j in current_users:
        if i.upper() == j.upper():#使用i.upper() == j.upper()，用忽略大小写的方式判断用户名是否相等
            print(
                "The user name %s has already been registered! Please change it and try again!"
                % i
            )
            break
    else:
        print("Congratulations, the user name %s is available!" % i)