python 基本语法

一、Hello World

　　python下的Hello World写法：

1 #!/usr/bin/env python
2 # _*_ coding: UTF-8 _*_
3 # Author:taoke
4 print("Hello world!!!")

[#!usr/bin/env python] 解释：
寻找linux系统下的python环境变量
[# _*_ coding: UTF-8 _*_] 解释：
当前文件使用UTF-8 编码
[# Author:taoke] 解释：
没错，就是我>_<


二、变量
　　变量定义的规则：
　　1、变量名只能够是数字、字母、下划线的任意组合
　　2、变量名的第一个字符不能够是数字
　　3、以下关键字不能够作为变量名
　　　　[and,as,assert,break,class,continue,def,del,elif,else,
　　　　 except,exec,finally,for,from,global,if,import,in,is,lambda,
　　　　 not,or,pass,print,raise,return,try,while,with,yield]
　　(python中没有常量的概念，个人定义把变量名全大写的变量作为常量来使用)


三、编码
　　ASCII编码 255 1bytes
　　　　-->1980 GB2312 2bytes
　　　　-->1995 GBK1.0 2w+
　　　　-->2000 GB18030 27xxx
　　　　-->1994 unicode 2bytes (万国码)
　　　　-->UTF8  en(ascii):1bytes 
　　　　　　　　　ch:3bytes


四、注释
1、# 注释内容
2、‘‘‘

   注释内容

   ’’’

五、用户交互程序（input和格式化输出）
字符串拼接尽量不使用，
用以下三种格式化输出的方式：

 1 #!/usr/bin/env python
 2 # _*_ coding: UTF-8 _*_
 3 # Author:taoke
 4 
 5 name = input("name:")
 6 job = input("job:")
 7 salary = input("salary:")
 8 age = int(input("age:"))
 9 print(type(age),type(str(age)))
10 outstr1 = """
11 ------info %s-------
12 name:%s
13 job:%s
14 salary:%s
15 age:%d
16 """%(name,name,job,salary,age)
17 outstr2 = """
18 ------info {_name}-------
19 name:{_name}
20 job:{_job}
21 salary:{_salary}
22 age:{_age}
23 """.format(_name = name,
24             _job = job,
25             _salary = salary,
26             _age = age)
27 outstr3 = """
28 ------info {0}-------
29 name:{0}
30 job:{1}
31 salary:{2}
32 age:{3}
33 """.format( name,
34             job,
35             salary,
36             age)
37 
38 print(outstr3)

六、猜年纪的游戏（while 和 if）

 1 #!/usr/bin/env python
 2 # _*_ coding: UTF-8 _*_
 3 # Author:taoke
 4 reallyAge = 43
 5 guessage = 0
 6 while guessage != reallyAge:
 7     guessage = int(input("please input guess age:"))
 8     if guessage<reallyAge:
 9         print("小了")
10     elif guessage>reallyAge:
11         print("大了")
12 else:
13     print("猜对了")

七、作业

1、编写登录接口

　　1）输入用户名密码

　　2）登录成功后显示欢迎信息

　　3）输错三次后锁定（即：输出用户已被锁定）

 1 #!/usr/bin/env python
 2 # _*_ coding: UTF-8 _*_
 3 # Author:taoke
 4 
 5 username = 'huangye'
 6 password = '123456'
 7 flag=0
 8 count = 0
 9 while True:
10     inputname = input("用户名：")
11     inputpassword = input("密码：")
12     if inputname == username:
13         if count<3:
14             if inputpassword == password:
15                 print("欢迎{_username}使用".format(_username = inputname))
16                 break
17             else:
18                 count+=1
19                 print("用户名或密码错误")
20         else:
21             print("用户已被锁定")
22     else:
23          print("用户名或密码错误")

2、编写一个多级菜单程序

1）三级菜单

2）可一次选择进入各级子菜单

 1 #!/usr/bin/env python
 2 # _*_ coding: UTF-8 _*_
 3 # Author:taoke
 4 #三级菜单
 5 dic_ = { "tap_main":("tap1","tap2","tap3"),
 6         "tap1":("tap1_1","tap1_2","tap1_3"),
 7         "tap2":("tap2_1","tap2_2","tap3_3"),
 8         "tap3":("tap3_1","tap3_2","tap3_3"),
 9         "tap1_1":('tap1_1 msg1','tap1_1 msg2','tap1_1 msg3'),
10         "tap1_2":('tap1_2 msg1','tap1_2 msg2','tap1_2 msg3'),
11         "tap1_3":('tap1_3 msg1','tap1_3 msg2','tap1_3 msg3'),
12         "tap2_1":('tap2_1 msg1','tap2_1 msg2','tap2_1 msg3'),
13         "tap2_2":('tap2_2 msg1','tap2_2 msg2','tap2_2 msg3'),
14         "tap2_3":('tap2_3 msg1','tap2_3 msg2','tap3_3 msg3'),
15         "tap3_1":('tap3_1 msg1','tap3_1 msg2','tap3_1 msg3'),
16         "tap3_2":('tap3_2 msg1','tap3_2 msg2','tap3_2 msg3'),
17         "tap3_3":('tap3_3 msg1','tap3_3 msg2','tap3_3 msg3'),
18        }
19 
20 menuName = "tap_main"
21 curmenu = "tap_main"
22 print(dic_[curmenu])
23 while True:
24     menuName = input("需要访问的菜单名：")
25     if menuName == 'b':
26         #输出上一级菜单
27         if curmenu == "tap_main":
28             print("输入错误")
29         elif curmenu == "tap1" or curmenu == "tap2" or curmenu == "tap3":
30             curmenu = "tap_main"
31         elif curmenu == "tap1_1" or curmenu == "tap1_2" or curmenu == "tap1_3":
32             curmenu = "tap1"
33         elif curmenu == "tap2_1" or curmenu == "tap2_2" or curmenu == "tap2_3":
34             curmenu = "tap2"
35         elif curmenu == "tap3_1" or curmenu == "tap3_2" or curmenu == "tap3_3":
36             curmenu = "tap3"
37     elif menuName == 'q':
38         break
39     else:
40         if menuName in dic_.keys():
41             curmenu = menuName
42         else:
43             print("输入错误")
44     print(dic_[curmenu])
45 
46 print("程序结束")