trying to match a string

Eddie Corns eddie at
Fri Jul 18 12:46:53 CEST 2008

arnimavidyarthy at writes:



>I am taking a string as an input from the user and it should only
>contain the chars:L , M or R

>I tried the folllowing in kodos but they are still not perfect:

>[LRM]?L?[LRM]? etc but they do not exactly meet what I need.

>For eg: LRLRLRLRLM is ok but LRLRLRNL is not as it has 'N' .like that.


>The string may or may not have all the three chars.

>>> var     = 'LRLRLRNL'
>>> residue = var.replace('L','').replace('R','').replace('M','')
>>> if residue != '':
...   print 'Invalid characters in input',residue
Invalid characters in input N

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