字符串操作练习：星座、凯撒密码、99乘法表、词频统计预处理

1. 实例：输出12个星座符号，以反斜线分隔。

   for i in range(12):
       print(chr(9800+i),end='\')

2. 实例：恺撒密码的编码

   plaincode = input('明文：')
   print('密文:',end='')
   for i  in plaincode:
       print(chr(ord(i)+3),end='')

3. 输入姓名，格式输出：占4位、居中、不足4字的以空格填充。

   a=input("姓名：")
   print("你输入的名字是：{0:^4}".format(a))

4. 格式化输出：中华人民共和国国内生产总值(GDP)689,136.89亿元(2015年)（千分位、2位小数，浮点数）

   print("中华人民共和国国内生产总值(GDP):{0:^-10,.3f}亿元".format(689,136.89))

5. 实例：打出99乘法表

   for i in range(1,10):
       for j in range(1,10):
            print("%d*%d=%2d" % (i,j,i*j),end=" ")
       print("")

6. 实例: 下载一首英文的歌词或文章，统计单词出现的次数，将所有,.？！替换为空格，将所有大写转换为小写。

   song='''
   Someone Like You - Adele
   I heard that you settled down
   我听说你已心有所属
   That you found a girl and your married now
   你找到了一个合适的女孩并和她结了婚
   I heard that your dreams came true
   我听说你已梦想成真
   Guess she gave you things I didn't give to you
   我猜，她给了你我所未能给予的
   Old friend why are you so shy
   老朋友，你害什么羞呢
   It ain't like you to hold back or hide from the lie
   不像你啊，遮遮掩掩的
   I hate to turn up out of the blue uninvited
   我恨她代替了原本属于我的位置
   But I couldn't stay away I couldn't fight it
   但是我没办法离开，我无法释怀
   I'd hoped you'd see my face & that you'd be reminded
   我曾多么希望你再看看我并提醒你
   That for me it isn't over
   并提醒你，对我来说，一切都还未结束
   Nevermind I'll find someone like you
   无所谓，我会找到一个人像你一样
   I wish nothing but the best for you too
   我别无所求，只希望你能过得好
   Don't forget me I beg I remember you said -
   求求你，不要忘记我我记得你说过
   Sometimes it lasts in love but sometimes it hurts instead
   有时爱情可以很永久但有时也会如此伤人
   Sometimes it lasts in love but sometimes it hurts instead yeah
   有时爱情可以很永久但有时也会如此伤人 是啊
   You'd know how the time flies
   你知道时光飞逝
   Only yesterday was the time of our lives
   仿佛我们还在一起
   We were born and raised in a summery haze
   我的爱在夏日的烟雾中萌芽
   Bound by the surprise of our glory days
   充满着惊喜和喜悦
   I hate to turn up out of the blue uninvited
   我恨她代替了原本属于我的位置
   But I couldn't stay away I couldn't fight it
   但是我没办法离开，我无法释怀
   I'd hoped you'd see my face & that you'd be reminded
   我曾多么希望你再看看我并提醒你
   That for me it isn't over yet
   对我来说，一切都还未结束
   Nevermind I'll find someone like you
   无所谓，我会找到一个人像你一样
   I wish nothing but the best for you too
   我别无所求，只希望你能过得好
   Don't forget me I beg I remember you said -
   求求你，不要忘记我我记得你说过
   Sometimes it lasts in love but sometimes it hurts instead
   有时爱情可以很永久但有时也会如此伤人
   Nothing compares no worries or cares
   没什么可与它相比不必担心 不必牵挂
   Regret's and mistakes they're memories made
   我们曾经的爱情里充满了遗憾和误解
   Who would have known how bittersweet this would taste
   又有谁能体会着中间的苦与甜
   Nevermind I'll find someone like you
   无所谓，我会找到一个人像你一样
   I wish nothing but the best for you too
   我别无所求，只希望你能过得好
   Don't forget me I beg I remembered you said -
   求求你，不要忘记我我记得你说过
   Sometimes it lasts in love but sometimes it hurts instead
   有时爱情可以很永久但有时也会如此伤人
   Nevermind I'll find someone like you
   无所谓，我会找到一个人像你一样
   I wish nothing but the best for you too
   我别无所求，只希望你能过得好
   Don't forget me I beg I remembered you said -
   求求你，不要忘记我我记得你说过
   Sometimes it lasts in love but sometimes it hurts instead
   有时爱情可以很永久但有时也会如此伤人
   Sometimes it lasts in love but sometimes it hurts instead yeah yeah
   有时爱情可以很永久但有时也会如此伤人
   -
   '''
   print(song.count("someone"))
   print(song.replace(',',' '))
   print(song.replace('.',' '))
   print(song.replace('?',' '))
   print(song.replace('!',' '))
   print(song.lower())

7. 用webbrowser，uweb.open_new_tab('url')打开校园新闻列表

   import webbrowser as web
   for i in range(2,6):
       web.open_new_tab('http://news.gzcc.cn/html/xiaoyuanxinwen/'+str(i)+'.html')