How can I tell when a string is in fact a number?

Joshua Muskovitz josh at open.com
Sun Nov 5 18:52:12 EST 2000


Why use re at all?

def isanum(str):
    import string
    return reduce(lambda x, y: x and y in string.digits, str, str != "")

>>> isanum("")
0
>>> isanum("1234")
1
>>> isanum("123xxx566")
0
>>> isanum("123.45")
0

This correctly handles the original problem of ensuring that the input
string contains *only* digits.  Of course, the original problem also
returned 1 for the empty input string ("").  To handle this, replace [str !=
""] with [1] in the reduce function.

why-does-everyone-always-try-to-present-a-solution-to-something-other-than-t
he-original-problem'ly yrs,

-- josh




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