题解 | #禁止重复注册#

def func_lower(name_list):   #整个函数专门用来将列表小写
    name_list = [name_list[i].lower() for i in range(len(name_list))]
    return name_list

current_users = ['Niuniu', 'Niumei', 'GURR', 'LOLO']
current_users_lower = func_lower(current_users) #不改变原列表，创建一个新列表装小写成员
new_users = ['GurR', 'Niu Ke Le', 'LoLo', 'Tuo Rui Chi']
new_users_lower = func_lower(new_users)

for i in range(len(new_users)):
    if new_users_lower[i] in current_users_lower:
        print(f'The user name {new_users[i]} has already been registered! Please change it and try again!')  #对照小写列表和原列表两个，根据位置相同去原列表找到元素，按要求打印出来
    else:
        print(f'Congratulations, the user name {new_users[i]} is available!')