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Posted by Katie Love   (19 posts)  [Biography] bio
Date Tue 24 Feb 2009 03:17 AM (UTC)
Is there a lua equivalent to the php is_numeric()?


I've been searching Google and these forums with no luck...

Any thoughts would be very helpful!

Thanks :-)
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Posted by WillFa   USA  (525 posts)  [Biography] bio
Date Reply #1 on Tue 24 Feb 2009 03:18 AM (UTC)
if tonumber(x) then ...

tonumber() returns a number or nil if it can't convert.
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Posted by Nick Gammon   Australia  (21,609 posts)  [Biography] bio   Forum Administrator
Date Reply #2 on Tue 24 Feb 2009 03:30 AM (UTC)
I agree with Willfa, that is an easy way.

However a bit depends on what you define as "numeric" in your application.

For example:

print (tonumber ("0xff"))  --> 255
print (tonumber ("1e6"))  --> 1000000

The value "0xff" is considered a numeric literal in Lua, and hence it converts. If you are really asking "how to test for 0 to 9 with an optional leading sign, you may be better off with a regular expression (ie. string.match).

- Nick Gammon

www.gammon.com.au, www.mushclient.com
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