流程控制--if条件

/* if ....else .... */
[root@localhost test1]# vim 5.py
//ADD
#!/usr/bin/python

if 1>2:
    print ‘hello python‘
    print ‘TRUE‘
else:
    print ‘FALSE‘

[root@localhost test1]# python 5.py
FALSE

/* elif 
如果if 不成立
     elif 成立，则执行elif

如果if不成立
     elif也不成立
      则执行else 
*/
[root@localhost test1]# vim 5.py
//ADD
#!/usr/bin/python

if 1>2:
    print ‘hello python‘
    print ‘TRUE‘
elif ‘a‘:
    print ‘b‘
else:
    print ‘FALSE‘

[root@localhost test1]# python 5.py
b
[root@localhost test1]# vim 5.py
//ADD
#!/usr/bin/python

if 1>2:
    print ‘hello python‘
    print ‘TRUE‘
elif 0:
    print ‘b‘
else:
    print ‘FALSE‘

[root@localhost test1]# python 5.py
FALSE

/*     利用 raw_input()输入或输出的是 字符串，

        始终 比整型数值大，所以当设计一个“分数脚本”时，没办法得出正确的结果

        可以利用 int(‘‘)这样的形式，将字符串转换为整型。
*/
[root@localhost test1]# vim 6.py
//ADD
#!/usr/bin/python

score = int(raw_input("Please input your score: "))
if score >= 90:
     print ‘A‘
     print ‘excellent‘
elif score >= 80:
     print ‘B‘
     print ‘very good‘

elif score >=70:
     print ‘C‘
     print ‘good‘
else:
     print ‘D‘
     print ‘Sorry,you failed.‘

[root@localhost test1]# python 6.py
Please input your score: 30
D
Sorry,you failed.
[root@localhost test1]# python 6.py
Please input your score: 70
C
good
[root@localhost test1]# python 6.py
Please input your score: 92
A
excellent
[root@localhost test1]# python 6.py
Please input your score: 83
B
very good

/* a.lower()  -- 这个lower()函数能够把大写的东西变成小写 */
[root@localhost test1]# vim 7.py
//ADD
#!/usr/bin/python

yn = raw_input("Please input [Yes/No]: ")
yn = yn.lower()
if yn == ‘y‘ or yn == ‘yes‘:
    print "programe is running..."
elif yn == ‘n‘ or yn == ‘no‘:
    print "programe is exit"
else:
    print "please input [Yes/No]"

[root@localhost test1]# python 7.py
Please input [Yes/No]: Yes
programe is running...
[root@localhost test1]# python 7.py
Please input [Yes/No]: No
programe is exit
[root@localhost test1]# python 7.py
Please input [Yes/No]: yes
programe is running...
[root@localhost test1]# python 7.py
Please input [Yes/No]: no
programe is exit
[root@localhost test1]# python 7.py
Please input [Yes/No]: ddd
please input [Yes/No]