1、字符串的函数join
>>> s = "Hello"
>>> s1 = s.join("你好")#将字符串Hello插入到你好中
>>> s1
'你Hello好'
>>> s2 = "Tanxu".join("你好吗")#将字符串Tanxu插入到你好吗中
>>> s2
'你Tanxu好Tanxu吗'
join可以把列表变成字符串
>>> s3 = "_".join(["Tanxu","is","a","good","student"])
>>> s3
'Tanxu_is_a_good_student'
2、list在循环的时候不能删,因为会改变索引
>>> lst = ["Tanxu","is","a","good","student"]
>>> for el in lst:lst.remove(el)>>> lst
['is', 'good']
要删除一个列表:
lst = ["Tanxu","is","a","good","student"]#准备一个空列表
del_lst = []
for el in lst:del_lst.append(el) #记录下来要删除的内容
for el in del_lst: #循环记录的内容lst.remove(el)#删除原来的内容
print(lst)
#删除以周开头的人
lst1 = ["周杰伦","周星驰","周润发","马化腾","马云"]del_lst1 = []
for el in lst1:del_lst1.append(el)for el in del_lst1:if "周" in el:lst1.remove(el)
print(lst1)
3、fromkeys用法:【不会对原来的字典产生影响】
>>> dic = {'a':'123'}
>>> s = dic.fromkeys("Hello","你好") #返回一个新的字典
>>> s
{'H': '你好', 'e': '你好', 'l': '你好', 'o': '你好'}
4、类型转换
元组--》类别 list(tuple)
列表转换成元组 tuple(list)
list==》str str.join(list)
str==>list str.split()
转换成False的数据:
0,'',None,[],(),{},set() ==》 False