Re: Isnumeric function?

How about this

CREATE OR REPLACE FUNCTION is_numeric ( text ) RETURNS bool AS '
if { [string is integer $1] || [string is double $1] } {
return true
}
return false
' LANGUAGE 'pltcl' IMMUTABLE;

SELECT is_numeric ( '-1' );
is_numeric
------------
t
(1 row)

SELECT is_numeric ( '+1e-1' );
is_numeric
------------
t
(1 row)

SELECT is_numeric ( '1.1.1' );
is_numeric
------------
f
(1 row)

--
Vadim Passynkov

-----Original Message-----
From: Jeff Eckermann [mailto:jeff_eckermann(at)yahoo(dot)com]
Sent: Thursday, September 09, 2004 10:02 AM
To: Thomas Swan; olly(at)lfix(dot)co(dot)uk
Cc: Josh Berkus; Theo Galanakis; pgsql-sql(at)postgresql(dot)org
Subject: Re: [SQL] Isnumeric function?

Ok, how about this. At least it works in my testing.
I have extended it to allow a negative sign (trailing
also), which I would expect to be allowed in a
comprehensive "isnumeric" function. If I am wrong,
feel free to slap me around; although correcting the
regex would be more constructive. ;-)

create function isnumeric(text) returns boolean as '
select $1 ~
\'(-?([0-9]+\\.?[0-9]*|[0-9]*\\.?[0-9]+)|([0-9]+\\.?[0-9]*|[0-9]*\\.?[0-9]+)
-?)\'
'language 'sql';

--- Thomas Swan <tswan(at)idigx(dot)com> wrote:

> Oliver Elphick wrote:
>
> >On Wed, 2004-09-08 at 18:48, Josh Berkus wrote:
> >
> >
> >>Theo, Oliver,
> >>
> >>
> >>
> >>>Any reason why you don't like ~
> '^([0-9]?)+\.?[0-9]*$' ?
> >>>
> >>>
> >>Yes, because it also matches "." , which is not a
> valid numeric value.
> >>
> >>
> >>
> >>> ~ '^([0-9]+|[0-9]+\\.[0-9]*|[0-9]*\\.[0-9]+)$'
> >>>
> >>>
> >>Ah, the brute force approach ;-)
> >>
> >>
> >
> >Nothing like using a nice big hammer!
> >
> >
> >
> Would "^([0-9]+\\.{0,1}[0-9]*|\\.[0-9]+)$" be a
> little cleaner?
>
> >>Actually, the above could be written:
> >>
> >>~ '^([0-9]+)|([0-9]*\\.[0-9]+)$'
> >>
> >>
> >
> >But that doesn't allow a trailing decimal point.
> >
> >
> >
> >>... though that still seems inelegant to me. Is
> there a regex expert in the
> >>house?
> >>
> >>
> >
> >All the elegant approaches I can think of match the
> empty string. There
> >must be at least one digit and 0 or 1 decimal point
> with no other
> >characters permitted. If you use this as a
> constraint, you could make
> >it elegant and combine it with another constraint
> to exclude '' and '.'.
> >
> >
>
>
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