Thread: Help with converting hexadecimal to decimal

Hi All,
  Is there a built in function which works exactly the opposite way as
to_hex().
I basically want to convert a a hexadecimal to a decimal.
Thanks

Chandra Sekhar Surapaneni wrote:
> Hi All,
>   Is there a built in function which works exactly the opposite way as
> to_hex().
> I basically want to convert a a hexadecimal to a decimal.

Sure:

    test=> SELECT x'10'::integer;
     int4
    ------
       16
    (1 row)

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Bruce Momjian <pgman@candle.pha.pa.us> writes:

> Chandra Sekhar Surapaneni wrote:
> > Hi All,
> >   Is there a built in function which works exactly the opposite way as
> > to_hex().
> > I basically want to convert a a hexadecimal to a decimal.
>
> Sure:
>
>     test=> SELECT x'10'::integer;
>      int4
>     ------
>        16
>     (1 row)

That's not the inverse of to_hex().  to_hex() takes an integer and
returns text.  You've taken the bitstring constant B'10000' and
coerced it to integer.  The inverse funtion would take the text '10'
and return the integer 16.

On 31 Mar 2005 21:22:12 -0600, Doug Quale <quale1@charter.net> wrote:
> > > I basically want to convert a a hexadecimal to a decimal.
> > Sure:
> >
> >       test=> SELECT x'10'::integer;
> >        int4
> >       ------
> >          16
> >       (1 row)

Oh, some time ago I was looking for such a function and somehow
I missed that.  Maybe there should be a hint about it around
string/numeric functions?

> That's not the inverse of to_hex().  to_hex() takes an integer and
> returns text.  You've taken the bitstring constant B'10000' and
> coerced it to integer.  The inverse funtion would take the text '10'
> and return the integer 16.

Well, you can make a function out of it, say:

CREATE FUNCTION from_hex(t text) RETURNS integer AS $$
  DECLARE
    r RECORD;
  BEGIN
    FOR r IN EXECUTE 'SELECT x'''||t||'''::integer AS hex' LOOP
      RETURN r.hex;
    END LOOP;
  END
$$ LANGUAGE plpgsql IMMUTABLE STRICT;

  Regards,
     Dawid

That's exactly what I am looking for. Thank you Dawid and everyone for
your help.
Regards
chandu

-----Original Message-----
From: Dawid Kuroczko [mailto:qnex42@gmail.com]
Sent: Friday, April 01, 2005 3:28 AM
To: Doug Quale
Cc: pgsql-general@postgresql.org
Subject: Re: [GENERAL] Help with converting hexadecimal to decimal

On 31 Mar 2005 21:22:12 -0600, Doug Quale <quale1@charter.net> wrote:
> > > I basically want to convert a a hexadecimal to a decimal.
> > Sure:
> >
> >       test=> SELECT x'10'::integer;
> >        int4
> >       ------
> >          16
> >       (1 row)

Oh, some time ago I was looking for such a function and somehow I missed
that.  Maybe there should be a hint about it around string/numeric
functions?

> That's not the inverse of to_hex().  to_hex() takes an integer and
> returns text.  You've taken the bitstring constant B'10000' and
> coerced it to integer.  The inverse funtion would take the text '10'
> and return the integer 16.

Well, you can make a function out of it, say:

CREATE FUNCTION from_hex(t text) RETURNS integer AS $$
  DECLARE
    r RECORD;
  BEGIN
    FOR r IN EXECUTE 'SELECT x'''||t||'''::integer AS hex' LOOP
      RETURN r.hex;
    END LOOP;
  END
$$ LANGUAGE plpgsql IMMUTABLE STRICT;

  Regards,
     Dawid

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