字符串练习

字符串练习：

http://news.gzcc.cn/html/2017/xiaoyuanxinwen_1027/8443.html

取得校园新闻的编号

>>> s="http://news.gzcc.cn/html/2017/xiaoyuanxinwen_1027/8443.html"
>>> s[45:54]
'1027/8443'

https://docs.python.org/3/library/turtle.html

产生python文档的网址

>>> s1="http://docs.python.org/3/library/"
>>> s2="turtle.html"
>>> s=s1+s2
>>> print(s)
http://docs.python.org/3/library/turtle.html
>>>

http://news.gzcc.cn/html/xiaoyuanxinwen/4.html

产生校园新闻的一系列新闻页网址

for i in range(2,231):

"http://news.gzcc.cn/html/xiaoyuanxinwen/{}.html".format(i)

练习字符串内建函数：strip,lstrip,rstrip,split,count

用函数得到校园新闻编号

方法一：

str="http://news.gzcc.cn/html/2017/xiaoyuanxinwen_1027/8443.html"

>>> str.replace('_','.').split('.')[3]

 '1027/8443'

方法二：

>>> str = 'http://news.gzcc.cn/html/2018/xiaoyuanxinwen_1027/8443.html'

>>> print(str.rstrip('.html')[-9:])
1027/8443

方法三：

>>> str = 'http://news.gzcc.cn/html/2018/xiaoyuanxinwen_1027/8443.html'

>>> print(str.rstrip('.html').split('_')[1])
1027/8443

用函数统计一歌词中单词出现的次数

>>> mus="""
I'm gonna stand right here
I'm not gonna lose
But when the sky falls down
You'll find me next to you
I'm gonna stand right here
And wait for you voice
But when the worlds
You know we got no choice, hey
When you hear the sound
Of the world of war
You know that you can see is a big red sky
When you know you can't make it on your own
I will be your soldier
When you falling down and your on the fence
I will be your shield that will keep you save
When you know you can't make it on your own
I will be your soldier
When you hear the sound
Of the world of war
You know that you can see is a big red sky
When you know you can't make it on your own
I will be your soldier
When you falling down and your on the fence
I will be your shield that will keep you save
When you know you can't make it on your own
I will be your soldier
I will be your soldier
I will be your soldier"""

>>> mus.count('soldier')
6

将字符串分解成一个个的单词。

>>> str="http://news.gzcc.cn/html/xiaoyuanxinwen/9.html"

>>> str.split('/')
['http:', '', 'news.gzcc.cn', 'html', 'xiaoyuanxinwen', '9.html']

>>> str.split('/',1)
['http:', '/news.gzcc.cn/html/xiaoyuanxinwen/9.html']
>>>

2.组合数据类型练习

分别定义字符串，列表，元组，字典，集合，并进行遍历。

字符串：

定义：

>>> str='spring'

遍历：
>>> for i in str : print(i)

s
p
r
i
n
g

列表：

定义：

>>> ls=list('5468')
>>> ls
['5', '4', '6', '8']

遍历：
>>> for i in ls: print(i)

5
4
6
8
>>>

元组：

定义：

>>> tup=tuple('Nacy')
>>> tup
('N', 'a', 'c', 'y')

遍历：
>>> for i in tup :print(i)

N
a
c
y
>>>

词典：

定义方法一：>>> dic1={}
>>> dic1['Michael']=80
>>> dic1['Nacy']=98
>>> dic1['Jake']=77
>>> dic1
{'Michael': 80, 'Nacy': 98, 'Jake': 77}
>>>

定义方法二：

>>> dic=dict(zip('tutle','48574888'))
>>> dic
{'t': '5', 'u': '8', 'l': '7', 'e': '4'}

遍历：

>>> for i in dic : print(i)

t
u
l
e

集合：

定义：

>>> s=set('Nacy')
>>> s
{'y', 'a', 'c', 'N'}

遍历：
>>> for i in s:print(i)

y
a
c
N
>>>

总结列表，元组，字典，集合的联系与区别。

 列表和元组的数据都是有序列的；词典和集合的数都是无序的；列表用[]括号；元组用（）括号；词典和集合都是用{}括号；遍历集合和词典时只会显示键（key）。