Python 常用代码片段

1.生成随机数            import random    #这个是注释，引入模块            rnd = random.randint(1,500)#生成1-500之间的随机数    2.读文件             f = open("c:\\1.txt","r")           lines = f.readlines()#读取全部内容           for line in lines                   print line  3.写文件          f = open("c:\\1.txt","r+")#可读可写模式          f.write("123")#写入字符串    4.正则表达式，读取tomcat的日志并打印日期         import re       regx = "\d\d\d\d-\d\d-\d+"       f = open("c:\stdout.log","r")       i = 0       for str in f.readlines():          if re.search(regx,str):               Response.write(str+"<br>")                if i>10:break#由于是测试，只分析十行                i=i+1       f.close();    5.连接数据库    import pgdb    conn = pgdb.connect    (host='localhost',databse='qingfeng',user='qingfeng',password='123')            cur = conn.cursor()             cur.execute("select * from dream")             print cur.rowcount    6.SAX处理xml:          import string        from xml.sax import saxlib, saxexts          class QuotationHandler(saxlib.HandlerBase):            """Crude sax extractor for quotations.dtd document"""              def __init__(self):                    self.in_quote = 0                    self.thisquote = ''              def startDocument(self):                print '--- Begin Document ---'              def startElement(self, name, attrs):                if name == 'quotation':                    print 'QUOTATION:'                    self.in_quote = 1                else:                    self.thisquote = self.thisquote + '{'              def endElement(self, name):                if name == 'quotation':                    print string.join(string.split(self.thisquote[:230]))+'...',                    print '('+str(len(self.thisquote))+' bytes)\n'                    self.thisquote = ''                    self.in_quote = 0                else:                    self.thisquote = self.thisquote + '}'              def characters(self, ch, start, length):                if self.in_quote:                    self.thisquote = self.thisquote + ch[start:start+length]          if __name__ == '__main__':            parser  = saxexts.XMLParserFactory.make_parser()            handler = QuotationHandler()            parser.setDocumentHandler(handler)            parser.parseFile(open("sample.xml"))            parser.close()      7.python的GUI模块标准的是Tkinter,也有QT和MFC的模块，有兴趣的大家自己搜索下            import Tkinter            root=Tkinter.Tk()            my=Label(root,"Welcome to python's world")            my.pack()            root.mainloop()