python学习exception

#-*- encoding: utf-8 -*-'''Created on 2013-1-7@author: '''#程序在执行的过程中产生异常，但不希望程序终止执行，这时就需要#用try和except 语句对异常进行处理。filename = ""while 1:    filename = raw_input("please input the filename")    if(filename == ""):        continue    try:        f=open(filename,"r")        print ("open the filename %s" % filename)    except:        print ("this is no filename: %s\n" % filename)      break        #自定义异常信息#raise有两个参数，第一个是由我们自己定义的异常类型，第二个是关于#此异常的少量说明信息  def inputage():    num = raw_input("input your age")    if(num<18 or num > 65):        raise "BadNum", "age is illeage"    return numprint inputage()