Python中的分支条件结构

1. if 

1 #!/usr/bin/env python
2 #-*- coding:utf-8 -*-
3 user=input('Please input your username : ')

if user=='admin':
    print('Nice')

2. if ... else ...

 #!/usr/bin/env python
 #-*- coding:utf-8 -*-
 user=input('Please input your username : ')
 pass=input('Please input your password: ')
 if user=='admin' and pass=='123456':
     print('Good')
 else:
     print('Bad')

3. if ... elif ... else ...

 #!/usr/bin/env python
 #-*- coding:utf-8 -*-
grade=(prompt='Please input your grade')
if grade>=85:
    print('Great')
elif garde<85 and grade>=70:
    print('Good')
else grade<70:
    print('Bad')