Python上个手

    Python，由吉多·范罗苏姆（Guido van Rossum）在1989打发圣诞节放假时间的一门“课余”编程项目，至今已有二十多年的历史，语法简洁清晰，深受喜爱；

1. 小窥
   

   # 查看版本
   python -V # 输出
   print "hello" # 输入
   str = raw_input("press any key")
   print str# 注释
   print "www.cnblogs.com" # link # 帮助
   dir(list)
   help(list)

2. 变量
   

   # 无需声明和删除，直接赋值；type为内置函数，查询类型；
   a = 10
   print a,type(a)
   a = “hello”
   print a,type(a)
   a += “ word”
   print a,type(a)

3. 列表、元组和词典
   

   #####
   # 1. 列表：list，数据如同STL <list>，下标从0开始，支持添加删除
   province = ['GuangDong', 'ZheJiang', 'HeNan', 'XinJang', 'HeiLongJiang']
   print province[2]
   province.append(‘HuBei’)
   delete province[1]# 访问支持：[下限：上限：步长]，上限不包括在内
   print province[:3]        # idx from 0 to 7
   print province[3:]          # idx from 3 to end
   print province[0:5:2]     # from 0 to 4 with 2 steps
   print province[3:0:-1]    # from 2 to 1 with -1 steps
   print province[-1]          # the last one
   print province[-3]          # the second one from last                    #####
   # 2. 元组：Tuples，如同list，不过不能改变；如12个月英文名之类的常量
   days = ('Morning','Afternoon','Night')
   print days,type(days)# 字符串是一种triple
   str = “Hello world”
   print str[2:5]#####
   # 3. 词典：Dictionaries， 如同hash, 元素结构为 key:value；如成绩
   stu_score = {'ZhangSan':34,'LiSi':98, 'WangWu':99}# 新增key:value
   str_score['LiLei'] = 100# 删除key
   delete str_score['ZhangSan']# 检查    
   if str_score.has_key(‘HanMeiMei’):print “got HanMeimei ”
   else print “not find HanMeiMei”# 打印所有key，values 
   print stu_score.keys(),str_score.values()
   values = stu_score.values()
   values.sort()
   print values,length(values)

4. 循环
   

   # Python中语句后无“；”结尾；无“｛｝”，通过TAB（4个空格）
   # 1. while
   a = 0
   while (a < 10)a += a+1;print a
   # 2. if
   y = True
   if y == True:print “y is true”
   elif y == False:print “y is false”
   else:print “value of y is error.”#3. For
   tmp = [1,’a’,’sdfa’,242]
   for value in tmpprint value# 判断符号 >, >=, <, <=, ==, !=, in

5. 函数
   

   # 定义函数show
   def show(list, info)for entry in list:print entryreturn input(info) + 1    # input输出数字
   # 表传指针，bulid-in传值
   list = [1,2,3]
   info = “press num: “
   def show (list, info)list[1]=3info = “changed”
   show(list, info)
   print list,info

6. 类
   

   # 定义类
   class Shapedef __int__(self, x, y): # 构造self.x = xself.y = ydef area():print self.x * self.y
   shape = Shape(100,20)
   class Square(Shape)    # 继承def __int__(self, x):self.x = self.y = x# 对象词典
   class_dic = {}     
   class_dic[“Shape”] = Shape(100,20)
   class_dic[“Square”] = Square(100,20)
   print class_dic[“Shape”].area
   print class_dic[“Square”].area

7. 模块
   

   # 模块：只定义集（库），比如变量、函数和类
   # 可以自定义模块和模块包
   import test_module
   import dir.module  # 相同类型放一个目录

8. 文件操作
   

   Ofile = open(‘file’, ‘r’)
   Ofile.seek(45,0)
   # 支持seek、tell, readline, readlins, wirte, close

9. 异常处理

try:a = input(“press characters”)
except NameError:print “input a num”

 

[Reference]

http://zh.wikipedia.org/zh-cn/Pythonhttp://www.sthurlow.com/python/http://www.cnblogs.com/vamei/archive/2012/05/28/2521650.html