I'm Sure There's A Better Way

Alex Martelli aleaxit at yahoo.com
Sat Jul 7 09:38:20 CEST 2001


"Tim Daneliuk" <tundra at tundraware.com> wrote in message
news:3B465858.CB7F38E8 at tundraware.com...
> I want a function to check a string to make sure it is a legitimate
> dollar amount.  Which means it follows these rules:
>
> First character is numeric or "-"
> At most, one "." is allowed and, if present, is followed by exactly two
digits
> All the remaining characters must be in the range "0" - "9"

These specs seem to be equivalent to:
    optional: -
    one or more digits
    optional: . followed by two digits
    end of string

This is very easy to express as a Regular Expression:
    r'-?\d+(\.\d\d)?$'

So one function to check any string to see if it satisfies
this pattern is:

def isDollar(astring):
    import re
    return re.match(r'-?\d+(\.\d\d)?$', astring)


Alex






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