Python学习笔记

学习内容来源于http://www.runoob.com/python/python-basic-syntax.html

1.安装Pycharm，注册码:

BIG3CLIK6F-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-iygsIMXTVeSyYkUxAqpHmymrgwN5InkOfeRhhPIPa88FO9FRuZosIBTY18tflChACznk3qferT7iMGKm7pumDTR4FbVVlK/3n1ER0eMKu2NcaXb7m10xT6kLW1Xb3LtuZEnuis5pYuEwT1zR7GskeNWdYZ0dAJpNDLFrqPyAPo5s1KLDHKpw+VfVd4uf7RMjOIzuJhAAYAG+amyivQt61I9aYiwpHQvUphvTwi0X0qL/oDJHAQbIv4Qwscyo4aYZJBKutYioZH9rgOP6Yw/sCltpoPWlJtDOcw/iEWYiCVG1pH9AWjCYXZ9AbbEBOWV71IQr5VWrsqFZ7cg7hLEJ3A==-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

小结：可安装汉化包，可设置中文编码。

2.Python 标识符

（1）下划线的使用

单下划线：  _foo  不能直接访问的类，需通过类接口访问；

双下划线： __foo  类的私有成员，（只有public成员可访问？或是基类成员可访问？）；

双下划线开头和结尾： __foo__  代表特殊方法的专用标识，比如构造函数；

小结：不太明白，跟C++的区别，后续学习到再加解释。

3.行和缩进

编译需要根据模块逻辑的语句严格缩进，不然编译报错；

一句话换行用 “ \ ”  ，比如 ：   count = one + \

      two + \

      three 

定义的数组和接口形参时{ }，[ ], ( )，不用 斜杠（\） 换行

4.对文本解码时抛异常

UnicodeDecodeError:'gbk' codec can't decode byte 0x9a in position 15558: illegal multibyte sequence

分析：window的dir指令会默认未GBK格式，utf-8的格式去解码必然会异常，故把文件编码成utf-8就好

解决方法： import codecs

   File_ptr = codecs.open('test.txt','r','utf-8')

5.用惯了linux，用python的正则匹配实现grep指令

import re

Str_out = "\n".join(re.findall('guid.*', input))

解析：使用re模块的正则匹配findall查找guid关键字,其中(.*)表示向后合并字符串，("\n".)表示每个正则匹配出来的字符串开头合并换行符

6.python操作EXCEL，需要导入模块xlrd（读），xlwt（写）

import xlwt,xlrd

data=xlwt.Workbook()     ##准备新建EXCEL

sheet1=data.add_sheet(u'sheet1',cell_overwrite_ok=True)  ##添加新表单

sheet1.write(X,Y,u'string')##指定单元格写指定编码的字符串，这里是utf-8

data.save('damo.xls') ##保存文件，xlsx格式保存时，office2013不能打开，故用xls格式

7.文件读取时因编码格式不同报如下异常

UnicodeDecodeError: 'gbk' codec can't decode byte 0x9a in position 14304: illegal multibyte sequence

解析：因为windows命令系统中的dir是GDK编码格式，所以遇到文件编码格式是GDK的时候，使用codecs模块读取文件为指定编码格式

import codecs

File_in=codecs.open(path,'r','utf-8')

input=File_in.read()

即可正常读取文件。

8.取当前时间

import datetime
i = datetime.datetime.now()
print ("当前的日期和时间是 %s" % i)
print ("ISO格式的日期和时间是 %s" % i.isoformat() )
print ("当前的年份是 %s" %i.year)
print ("当前的月份是 %s" %i.month)
print ("当前的日期是  %s" %i.day)
print ("dd/mm/yyyy 格式是  %s/%s/%s" % (i.day, i.month, i.year) )
print ("当前小时是 %s" %i.hour)
print ("当前分钟是 %s" %i.minute)
print ("当前秒是  %s" %i.second)