str ----> list  split()      ()里有没有内容整个变成列表，（）里有内容按内容分割成列表内元素，且（）里内容不存在例如：
s = 'alex,wusir,taibai'
l1 = s.split()
print(l1)             输出结果：['alex,wusir,taibai']
l2 = s.split(',')
print(l2)            输出结果：['alex', 'wusir', 'taibai']
l3 = s.split('a')
print(l3)            输出结果：['', 'lex,wusir,t', 'ib', 'i']list ----> str   用 ''.join()例如：
li = ['alex','wusir','taibai']
s1 = ''.join(li)
print(s1)           输出结果：alexwusirtaibai
s2 = '_'.join(li)
print(s2)             输出结果：alex_wusir_taibai

tu = (1,2,3,{},[])
l1 = list(tu)
print(l1)             输出结果：[1, 2, 3, {}, []]li = [1,2,3,{},()]
t1 = tuple(li)
print(t1)             输出结果：(1, 2, 3, {}, ())

dic = {'k1':'alex','k2':'太白','k3':'日天','name':'wusir'}
print(dic.keys())             输出结果：dict_keys(['k1', 'k2', 'k3', 'name'])
print(list(dic.keys()))       输出结果：['k1', 'k2', 'k3', 'name']
print(dic.values())           输出结果：dict_values(['alex', '太白', '日天', 'wusir'])
print(list(dic.values()))     输出结果：['alex', '太白', '日天', 'wusir']
print(dic.items)              输出结果：不能这样写，需要两个变量接收
print(list(dic.items()))      输出结果：[('k1', 'alex'), ('k2', '太白'), ('k3', '日天'), ('name', 'wusir')]

li = [111,222,333,444,555]      #将索引为奇数位的元素删除.
# 第一种：
del li[1::2]
print(li)# 第二种：
li = [111,222,333,444,555]
l2 = []
for i in range(len(li)):if i % 2 == 0:l2.append(li[i])
li = l2
print(li)# 第三种：
li = [111,222,333,444,555]
for i in range(len(li)-1,0,-1):      #倒着删除的时候索引不会发生变化，所以不会报错if i % 2 == 1:del li[i]
print(li)

#第一种
dic1 = {1:'alex',2:['a','b'],3:('c','d')}
dic2 = dic1.copy()
dic1[1] = 'taibai'
print(dic1)             输出结果：{1: 'taibai', 2: ['a', 'b'], 3: ('c', 'd')}
print(dic2)             输出结果：{1: 'alex', 2: ['a', 'b'], 3: ('c', 'd')}#第二种
dic1 = {1:'alex',2:['a','b'],3:('c','d'),4:{'name':'zhu','age':18}}
dic2 = dic1.copy()
dic1[4]['name'] = 'taibai'
print(dic1)            输出结果：{1: 'alex', 2: ['a', 'b'], 3: ('c', 'd'), 4: {'name': 'taibai', 'age': 18}}
print(dic2)            输出结果：{1: 'alex', 2: ['a', 'b'], 3: ('c', 'd'), 4: {'name': 'taibai', 'age': 18}}

import copy
dic1 = {1:'alex',2:['a','b'],3:('c','d'),4:{'name':'zhu','age':18}}
dic2 = copy.deepcopy(dic1)
dic1[1] = 'taibai'
dic1[4]['name'] = 'wusir'
print(dic1)            输出结果：{1: 'taibai', 2: ['a', 'b'], 3: ('c', 'd'), 4: {'name': 'wusir', 'age': 18}}
print(dic2)            输出结果：{1: 'alex', 2: ['a', 'b'], 3: ('c', 'd'), 4: {'name': 'zhu', 'age': 18}}