FUNCTION valid_num, string, value, INTEGER=integer
 On_error,2
 compile_opt idl2

; A derivation of the regular expressions below can be found on
; http://wiki.tcl.tk/989

   if keyword_set(INTEGER) then $
    st = '^[-+]?[0-9][0-9]*$'  else $                    ;Integer
     st = '^[-+]?([0-9]+\.?[0-9]*|\.[0-9]+)([eEdD][-+]?[0-9]+)?$' ;F.P.

;Simple return if we just need a boolean test.
    if N_params() EQ 1 then return, stregex(strtrim(string,2),st,/boolean)


      vv = stregex(strtrim(string,2),st,/boolean)
      if size(string,/N_dimen) EQ 0 then begin     ;Scalar
         if vv then $
            value= keyword_set(integer) ? long(string) : double(string)
      endif else begin                             ;Array

      g = where(vv,Ng)
      if Ng GT 0 then begin      ;Need to create output vector
        if keyword_set(integer) then begin
              value = vv*0L
              value[g] = long(string[g])
        endif else begin
                value = replicate(!VALUES.D_NAN,N_elements(vv))
                value[g] = double(string[g])
        endelse
        endif
        endelse

       return,vv
      end