Verifying data type

Hello guys,

I have a function like this

CREATE OR REPLACE FUNCTION "public"."f_tipo_campo" (varchar) RETURNS
numeric AS
'declare
p_valor ALIAS FOR $1;
v_resultado varchar;
begin
v_resultado := 1;
<> return v_resultado;
<>end;
<><>' LANGUAGE 'plpgsql'

<>

<>
I need to verify if the data in p_valor is just number or it is a string.
What is the best way to do this?

Here is the original function in Oracle PL/SQL

create or replace function f_tipo_campo (p_valor varchar) return number is

v_resultado number;

v_number number;

begin

begin

select p_valor

into v_number from dual;

v_resultado := 0;

exception

when others then

v_resultado := 1;

end;

return v_resultado;

end;

/

show err

--
Elieser Leão
Sorry for my bad english...