4-1 判断

Posted 2021-01-22 hushaoyan

1、非空即真，非0即真

 1 # 非空即真，非0即真
 2 # True ‘1‘ [1] {k - v}
 3 # False ‘‘ None [] {]
 4 
 5 username = input(‘username:‘).strip()
 6 print(len(username) > 0)  # 非空即真
 7 # if username:
 8 #     print(‘username不为空‘)
 9 # else:
10 #     print(‘username为空‘)
11 
12 if 1:  # 非0即真
13     print(‘true‘)
14 else:
15     print(‘false‘)