个人笔记20181028

1 #检查用户名是否重复
2 current_users=[‘admin‘,‘alex‘,‘lebran‘,‘kaobi‘,‘James‘]
3 lower_current_users=[current_user.lower() for current_user in current_users]#列表元素变为小写
4 new_users=[‘Admin‘,‘alex‘,‘haden‘,‘Holliday‘,‘JAMES‘]
5 for new_user in new_users:
6     if new_user.lower() in lower_current_users:
7         print(‘Input another username.‘)
8     else:
9         print(‘You can use it.‘)

1 list=[‘admin‘,‘alex‘,‘lebran‘,‘kaobi‘,‘james‘]
2 list=[]  #将列表清空
3 if list:
4     print(‘h‘)
5 else:
6     print(‘We need to find some users!‘)

 1 numbers=list(range(1,10))
 2 for number in numbers:
 3     if number == 1:
 4         print(‘1st\n‘)
 5     elif number == 2:
 6         print(‘2nd\n‘)
 7     elif number == 3:
 8         print(‘3rd\n‘)
 9     elif number == 4:
10         print(‘4th\n‘)