Python字符串操作

时间：2025-04-22 09:06:25
  1. isalnum()判断是否都是有效字符串 
    >>> ev1 = 'evilxr'
    
>>> ev2 = 'ev1il2xr3'
    
>>> ev3 = '.,/!@#'
    
>>> a = ev1.isalnum()
    
>>> print a
    
True
    
>>> b = ev2.isalnum()
    
>>> print b
    
True
    
>>> c = ev3.isalnum()
    
>>> print c
    
False
  2. isalpha和isdigit可分别判断字符串里是否都是由字符或者数字组成 
    >>> ev1.isalpha()
    
True
    
>>> ev2.isalpha()
    
False
    
>>> ev2.isdigit()
    
False
    
>>> ev3.isdigit()
    
False
    
>>> ev2.isalpha()
    
False
    
>>> ev4.isdigit()
    
True
    
>>> ev4.isalpha()
    
False
    
>>>

    可以用来检测密码的强度~

    >>> xr = raw_input('Please input your password:')
    
Please input your password:evilxr1234
    
>>> xr.isalpha()
    
False
    
>>> xr.isdigit()
    
False
    
>>> xr.isalnum()
    
True
    
>>>
  3. 判断字符的大小写 
    >>> xr = raw_input('Please input your password:')
    
Please input your password:EVILXR
    
>>> xr.islower()    #xr的内容是小写的吗？
    
False
    
>>> xr.isupper()      #xr的内容是大写的吗？
    
True
    
>>>
  4. 判断是否全由空格组成 
    >>> xr1 = '          '
    
>>> xr1.isspace()
    
True
    
>>> xr2 = '  evilxr  '
    
>>> xr2.isspace()
    
False
    
>>>
  5. 字符的大小写转换 
    >>> 'evilxr'.upper()    #将小写字符全转换为大写
    
'EVILXR'
    
>>> 'HEY,WELCOME TO MY BLOG!'.lower()    #将大写字符全转换为小写
    
'hey,welcome to my blog!'
    
>>> 'Hey,My name is Evilxr!'.upper()    #大小写混合的也能转
    
'HEY,MY NAME IS EVILXR!'
    
>>> 'Hey,My name is Evilxr!'.lower()
    
'hey,my name is evilxr!'
    
>>>
  6. 去掉字符串左面或者右面的空格 
    [root@localhost test]# cat 1.py
    
ev1 = ' ev il xr '
    
print ev1
    
ev2 = ev1.lstrip()    #去掉左边
    
print ev2
    
ev3 = ev1.rstrip()    #去掉右边
    
print ev3

[root@localhost test]# python 1.py
    
 ev il xr
    
ev il xr
    
 ev il xr
  7. 判断字符串的开始和结束 
    [root@localhost test]# cat 2.py
    
s1 = '.com'
    
s2 = '.cn'
    
s3 = 'www.'
    
s4 = 'www.evilxr.com'

if s4.startswith(s3):
    
	print 'startswith www'
    
else:
    
	print 'start is not www'
    
if s4.endswith(s1):
    
	print 'endswith is com'
    
elif s2.endswith(s2):
    
	print 'endswith is cn'
    
else:
    
	print 'endswith is not com and cn'
    
[root@localhost test]# python 2.py
    
startswith www
    
endswith is com
    
[root@localhost test]#
    
 
  8. replace()函数的使用，值拷贝 
    >>> ev = 'www.evilxr.com'
    
>>> id (ev)
    
3078278264L
    
>>> s1 = ev.replace('e','E')
    
>>> print s1
    
www.Evilxr.com
    
>>> id(s1)
    
3078278584L
    
>>> ev1 = ev.replace('ev','EV')
    
>>> print ev1
    
www.EVilxr.com
    
>>> id(ev1)
    
3078278504L

    >>> ev2 = ev.replace('evilxr','evilxr.upper()')#upper()被当成了要被替换内容的一部分
    
>>> print ev2
    
www.evilxr.upper().com
    
>>> ev3 = ev.replace('evilxr','evilxr'.upper())#正确的应该是这个
    
>>> print ev3
    
www.EVILXR.com
    
>>> id(ev2)
    
3078232832L
    
>>> id(ev3)
    
3078278704L
    
>>>

    #用切片看下
    
>>> ev = 'evilxr'
    
>>> ev1 = ev[:3]
    
>>> print ev1
    
evi
    
>>> ev2 = ev[4:]
    
>>> print ev2
    
xr
    
>>> ev3 = ev[:3]+'L'+ev[4:]
    
>>> print ev3
    
eviLxr
  9. 域名匹配 
    re.match(r'^(?:[a-zA-Z0-9][a-zA-Z0-9\-]*\.)*([a-zA-Z0-9][a-zA-Z0-9\-]*?\.[a-zA-Z]{2,6}(?<!\.cn)(?:\.cn)?)$', 'a.b.124.ttt.com.cn').groups()
  10. python的json.dumps输出中文，指定ensure_ascii参数为False 
    Signature: json.dumps(obj, skipkeys=False, ensure_ascii=True, check_circular=True, allow_nan=True, cls=None, indent=None, separators=None, encoding='utf-8', default=None, sort_keys=False, **kw)

--------------------------------------------------------------------------------------------------------
    
In [11]: print json.dumps({'test':"西戎的博客园"},ensure_ascii=False)
    
{"test": "西戎的博客园"}

In [12]: print json.dumps({'test':"西戎的博客园"})
    
{"test": "\u897f\u620e\u7684\u535a\u5ba2\u56ed"}

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