Regular expression to match 3 capital letters followed by a small letter followed by 3 capital letters? [closed]

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I need a regular expression开发者_如何学编程 in python which matches exactly 3 capital letters followed by a small letter followed by exactly 3 capital letters. For example, it should match ASDfGHJ and not ASDFgHJK.

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r'\b[A-Z]{3}[a-z][A-Z]{3}\b'

This will match what you posted if it is a complete word.

r'(?<![^A-Z])[A-Z]{3}[a-z][A-Z]{3}(?![A-Z])'

This will match what you posted so long as it's not preceded or followed by another capital letter.

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here it is:

'[A-Z]{3}[a-z]{1}[A-Z]{3}'

Edited you need to use word boundary also:

r'\b[A-Z]{3}[a-z]{1}[A-Z]{3}\b'

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re.findall(r'[a-z][A-Z]{3}([a-z])[A-Z]{3}[a-z]', data)

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This is will check that one small character is exactly present between 3 capital characters on both sides.

I have used lookahead and lookbehind to ensure that exactly three capital characters are on both sides.

r'(?<![A-Z])[A-Z]{3}[a-z][A-Z]{3}(?![A-Z])'.

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>>> import re
>>> pattern = r'^[A-Z]{3}[a-z]{1}[A-z]'
>>> re.match(pattern , "ABCaABC").start()
    0
>>> print re.match(pattern , "ABCABC")
    None
>>> print re.match(pattern , "ABCAABC")
    None
>>> print re.match(pattern , "ABCAaABC")
    None
>>> print re.match(pattern , "ASDFgHJK")
    None
>>> print re.match(pattern , "ABCaABC")
    <_sre.SRE_Match object at 0x011ECF70>

r'^[A-Z]{3}[a-z]{1}[A-z]'
^ ->Start with capital, so First three letters must be capital.