Python笔记

    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 = 10print 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 7print province[3:]          # idx from 3 to endprint province[0:5:2]     # from 0 to 4 with 2 stepsprint province[3:0:-1]    # from 2 to 1 with -1 stepsprint province[-1]          # the last oneprint 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triplestr = “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:valuestr_score['LiLei'] = 100# 删除keydelete 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. whilea = 0while (a < 10)        a += a+1;        print a# 2. ify = Trueif y == True:        print “y is true”elif y == False:        print “y is false”else:        print “value of y is error.”#3. Fortmp = [1,’a’,’sdfa’,242]for value in tmp        print value# 判断符号 >, >=, <, <=, ==, !=, in

5. 函数
   

   # 定义函数showdef show(list, info)        for entry in list:            print entry        return 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]=3        info = “changed”show(list, info)print list,info

6. 类
   

   # 定义类class Shape        def __int__(self, x, y): # 构造            self.x = x            self.y = y        def area():            print self.x * self.yshape = 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”].areaprint 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_moduleimport 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