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Python字符串操作

2024-07-07 03:45:02   237人阅读

  1. isalnum()判断是否都是有效字符串
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    >>> 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
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    >>> 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~

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    >>> 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
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    >>> 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
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    >>> xr1 = ‘          ‘
    >>> xr1.isspace()
    True
    >>> xr2 = ‘  evilxr  ‘
    >>> xr2.isspace()
    False
    >>>
  5. 字符的大小写转换
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    >>> ‘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
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    [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
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    [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
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    >>> 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
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    >>> 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
    >>>
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    #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

     


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