re4lm

Regextest_example.py

u0_a200@grouper:/ $ python
Python 3.2.2 (default, Jun 23 2014, 00:13:13)
[GCC 4.8] on linux-armv7l
Type "help", "copyright", "credits" or "license" for more information.
>>> import re
>>> re.match('^[a-z0-9]{8}$', '878h76t5')
<_sre.SRE_Match object at 0x405ec480>
>>> re.match('^[a-z0-9]{8}$', '8786h76t5')
>>> re.match('^[a-z0-9]{8}$', '8786h76X5')
>>> s='ide az input'
>>> if re.match('^[a-z0-9]{8}$', s) != None: print(True)
...
>>>
>>> s='6g5f4d3s'
>>> if re.match('^[a-z0-9]{8}$', s) != None: print(True)
...
True
>>>

^[a-z0-9]{8}$ explained:

• ^ beginning of the string
• [a-z0-9] any single char which is between a-z or 0-9
• {8} 8 times that
• $ end of string

Also note that ^ and $ are necessary, because otherwise it would match '82838383838' too, as it contains our pattern.