查看str内部功能，可通过和int一样的方法，或者使用type(str)、dir(str)来查看。
1、capitalize：首字母大写
S.capitalize() -> string
str1 = "parr" result = str1.capitalize() print(result) #返回Parr
2、center(self, width, fillchar=None)：内容居中，width：总长度；fillchar：空白处填充内容（默认无）
S.center(width[, fillchar]) -> string
str1 = "parr" result = str1.center(10,"*") print(result) #返回***parr***
3、count(self, sub, start=None, end=None)：str的子序列个数，区分大小写
S.count(sub[, start[, end]]) -> int
str1 = "parrAbcadb"
result = str1.count("a")
print(result)
#返回2，表示找到两个a
4、decode(self, encoding=None, errors=None)：解码
S.decode([encoding[,errors]]) -> object
str1 = "哈哈" result = str1.encode() str2 = result.decode() print(str2) 屏幕打印：哈哈
5、encode(self, encoding=None, errors=None)：编码
S.encode([encoding[,errors]]) -> object
str1 = "哈哈" result = str1.encode() print(result) #返回b‘\xe5\x93\x88\xe5\x93\x88‘
6、endswith(self, suffix, start=None, end=None)：受否以XX结束，返回bool型的值
S.endswith(suffix[, start[, end]]) -> bool
str1 = "parr Luck 2017"
result = str1.endswith("2017")
print(result)
#屏幕打印Ture
7、expandtabs(self, tabsize=None)：将Tab转换为空格，默认一个Tab八个空格
S.expandtabs([tabsize]) -> string
str1 = "parr\thello" result = str1.expandtabs() print(result) 屏幕打印：parr hello
8、find(self, sub, start=None, end=None)：寻找子序列位置，如没找到返回-1
S.find(sub [,start [,end]]) -> int
str1 = "parr" result = str1.find(‘a‘) print(result) #屏幕打印1，表示a在1位置
9、isalnum(self)：是否是字母或数字，返回bool型的值
S.isalnum() -> bool
str1 = "parr2017" result = str1.isalnum() print(result) #屏幕打印：Ture
10、isalpha(self): ：是否是字母
S.isalpha() -> bool
str1 = "parr" result = str1.isalpha() print(result) #屏幕打印：Ture
11、isnumeric(self)：是否是数字
S.isnumeric() -> bool
str1 = "2017" result = str1.isnumeric() print(result) #屏幕打印Ture
12、islower(self)：是否是小写
isupper(self):：是否是大写
S.islower() -> bool
str1 = "parr" result = str1.islower() print(result) #返回Ture str1 = "parr" result = str1.isupper() print(result) #返回False
13、replace(self, old, new, count=None)：替换内容
S.replace(old, new[, count]) -> string
str1 = "parr" result = str1.replace(‘a‘,‘hello‘) print(result) #屏幕打印：phellorr
14、split(self, sep=None, maxsplit=None)：分割内容，maxsplit最多分割几次，返回一个列表
S.split([sep [,maxsplit]]) -> list of strings
str1 = "parr" result = str1.split(‘a‘) print(result) #返回[‘p‘, ‘rr‘]
15、splitlines(self, keepends=False):：根据换行分割，返回一个列表
S.splitlines(keepends=False) -> list of strings
str1 = """parr
hello
everyone
"""
result = str1.splitlines()
print(result)
#返回[‘parr‘, ‘ hello‘, ‘ everyone‘]
16、startswith(self, prefix, start=None, end=None)：是否起始为prefix中的内容
S.startswith(prefix[, start[, end]]) -> bool
str1 = """parr
hello
everyone
"""
result = str1.startswith(‘parr‘)
print(result)
#返回Ture
17、strip(self, chars=None)：移除两端空白
S.strip([chars]) -> string or unicode
str1 = " parr2017 " result = str1.strip() print(result) #返回parr2017
18、__contains__(self, y)：检查y是否包含于x中
x.__contains__(y) <==> y in x