python字符串的方法
############7个基本方法############
1：join
1 def join(self, ab=None, pq=None, rs=None): # real signature unknown; restored from __doc__
2 """
3 Concatenate any number of strings.
4
5 The string whose method is called is inserted in between each given string.
6 The result is returned as a new string.
7
8 Example: '.'.join(['ab', 'pq', 'rs']) -> 'ab.pq.rs'
9 """
10 可以向字符串插入 标识符 标点 字母等连接
test=("qweqweqw")
v="_".join(test)
print(v)
q_w_e_q_w_e_q_w
test=(['as','df','as'])
v="_".join(test)
print(v)
as_df_as
2：split（正则）
1 split(self, *args, **kwargs): # real signature unknown
2 """
3 Return a list of the words in the string, using sep as the delimiter string.
4
5 sep
6 The delimiter according which to split the string.
7 None (the default value) means split according to any whitespace,
8 and discard empty strings from the result.
9 maxsplit
10 Maximum number of splits to do.
11 -1 (the default value) means no limit.
12 """
13 全分割 从第一个逐一扫描字符串寻找所选字符 从字符串中找到该字符位置开始分割 （所选字符消失）
test=("asdfasdfasdfsadfsdf")
v=test.split("f")
print(v)
['asd', 'asd', 'asd', 'sad', 'sd', '']
test=("asdfasdfasdf")
v=test.split("s",2,)
print(v)
['a', 'dfa', 'dfasdf']
3：find
find(self, sub, start=None, end=None): # real signature unknown; restored from __doc__
"""
S.find(sub[, start[, end]]) -> int
Return the lowest index in S where substring sub is found,
such that sub is contained within S[start:end]. Optional
arguments start and end are interpreted as in slice notation.
Return -1 on failure.
"""
return 0
从左向右查找所定义的字符 显示首个该字符的索引（下标）；find（字符，开始索引，结束索引）
test=("asdfasdfasdfsadfsdf")
v=test.find("f")
print(v)
3
test=("asdfasdfasdfsadfsdf")
v=test.find("f",5,15)
print(v)
7
4：strip
strip(self, *args, **kwargs): # real signature unknown
"""
Return a copy of the string with leading and trailing whitespace remove.
If chars is given and not None, remove characters in chars instead.
"""
清除字符串两边的空格
test=(" asdfasdfas dfsadfsdf ")
v=test.strip()
print(v)
asdfasdfas dfsadfsdf
5：upper
upper(self, *args, **kwargs): # real signature unknown
""" Return a copy of the string converted to uppercase. """
字符串全大写
test=("asdfasdfasdfsadfsdf")
v=test.upper()
print(v)
ASDFASDFASDFSADFSDF
6：lower
lower(self, *args, **kwargs): # real signature unknown
""" Return a copy of the string converted to lowercase. """
pass
字符串全小写
test=("ASDFASDFASDFSADFSDF")
v=test.lower()
print(v)
asdfasdfasdfsadfsdf
7：replace
replace(self, *args, **kwargs): # real signature unknown
"""
Return a copy with all occurrences of substring old replaced by new.
count
Maximum number of occurrences to replace.
-1 (the default value) means replace all occurrences.
If the optional argument count is given, only the first count occurrences are
replaced.
"""
替换所选字符 replace（“文本内的字符”，“想要替换文本的字符”，“替换的数量”）
test=("ASDFASDFASDFSADFSDF")
v=test.replace("ASD","aaa",1)
print(v)
aaaFASDFASDFSADFSDF
test=("ASDFASDFASDFSADFSDF")
v=test.replace("ASD","aaa")
print(v)
aaaFaaaFaaaFSADFSDF