python3字符串操作总结

>>>s = 'hello'
>>>s[0:3]
'he' 
>>>s[:] #截取全部字符
'hello'
 

s.strip() #消除字符串s左右两边的空白字符（包括'\t'，'\n','\r',''）
 
s.strip('0') #消除字符串s左右两边的特殊字符（如'0'）,字符串中间的'0'不会删除

>>>s = '000hello00world000'
>>>s.strip('0')
'hello00world'
s.strip('12')等价于s.strip('21')

>>>s = '12hello21'
>>>s.strip('12')
'hello'

s1 = 'hello'
s2 = s1 # s2 = 'hello'

s1 = 'hello'
s2 = s1[0:2] #s2 = 'he'

s1 = 'hello'
s2 = 'world'
s3 = s1 + s2 #s3 = 'helloworld'

import operator
s3 = operator.concat(s1,s2) #concat为字符串拼接函数

>>>import operator
>>>operator.eq('abc','edf') #根据ASCII码比较
Flase
>>>operator.gt('abc','ab')
True

>>>s1 = 'abc'
>>>s2 = 'ab'
>>>s1 > s2
True
>>>s1 == s2
False

>>>s1 = 'hello'
>>>len(s1)
5

>>>s1 = 'hello'
>>>max(s1) #求字符串s1中最大字符
'o'
>>>min(s1) #求字符串s2中最小字符
'e'

>>>s1 = 'hello'
>>>s2 = 'WORLD'
>>>s3 = 'hello world'
>>>s1.upper() 
'HELLO'
>>>s2.lower() 
'world'
>>>s3.title() 
'Hello World'
>>>s3.capitalize() 
'Hello world'
>>>s3.title().swapcase() 
'hELLO wORLD'

>>>s1 = 'hello'
>>>s1[::-1]
'olleh'

>>>s1 = 'hello,world'
>>>s1.split(',')
['hello','world']

>>>l = ['hello','world']
>>>str = '-'
>>>str.join(l)
'hello-world'

>>>s1 = 'today is a fine day'
>>>s1.find('is')
6
>>>s1.find('is',3)
6
>>>s1.find('is',7,10)
-1

str.replace(old,new[,max]) #old为旧串，new为新串，max可选，为替换次数

>>>s1 = 'today is a find day'
>>>s1.replace('find','rainy')
'today is a rainy day'

>>>s1 = 'hello'
>>>s1.islower()
True
>>>s1.isdigit()
False

a = 'My name is Jason'
#使用split(str="", num=string.count(str)) 方法根据不同的分割符转，也可指定分割次数，可使用 ' '.join方法转回
>>> 'My name is Jason'.split(' ')
['My', 'name', 'is', 'Jason']
>>> ' '.join(['My', 'name', 'is', 'Jason'])
'My name is Jason'

>>> 'cat.jpg'.startswith('cat')
True
>>> 'cat.jpg'.startswith('cat',0,3)
True
>>> 'cat.jpg'.endswith('.jpg')
True
>>> 'cat.jpg'.endswith('.jpg',-4)
True

>>> s = ' Hello World  '
>>> s.strip()
'Hello World'
>>> s.lstrip()
'Hello World  '
>>> s.rstrip()
' Hello World'
#扩展
>>> 'www.example.com'.lstrip('www.')
'example.com'
>>> 'www.example.com'.lstrip('cmowz.')
'example.com'

#字符串的格式化
>>> '{name},{sex},{age}'.format(age=15,sex='male',name='小安')
'小安,male,15'
>>> '{1},{0},{2}'.format('15','小安','male')
'小安,15,male'
>>> '{},{},{}'.format('小安', '15','male')
'小安,15,male'

#如果字符串中的所有字符都是数字，并且至少有一个字符，则返回真，否则返回假
>>> '123'.isdigit()
True
>>> '123一二三'.isdigit()
False
#isnumeric 是所有字符都是数字字符返回真
>>> '123一二三'.isnumeric()
True

#字符串是否大小写判断
>>> 'abc'.islower()
True
>>> 'Abc'.islower()
False
>>> 'ABC'.isupper()
True

#首字母大写
>>> "they're bill's friends from the UK".title()
"They'Re Bill'S Friends From The Uk"
#正则处理方式
>>> import re
>>> def titlecase(s):
...   return re.sub(r"[A-Za-z]+('[A-Za-z]+)?",
...          lambda mo: mo.group(0)[0].upper() +
...               mo.group(0)[1:].lower(),
...          s)
...
>>> titlecase("they're bill's friends.")
"They're Bill's Friends."

#返回指定长度字符串，前面补0，一般存csv文件中含00开头的字符0会被抹掉
>>> code = '1'
>>> code.zfill(6)
'000001'

#字符串长度及遍历
>>> s = '混蛋哥'
>>> len(s)
3
>>> for i in s:
  print(i)
混
蛋
哥
>>>