Pandigital prime

Pandigital prime is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.

Task

The following problem is taken from Project Euler.
We shall say that an n-digit number is pandigital if it makes use of all the digits 1 to n exactly once.
For example, 2143 is a 4-digit pandigital and is also prime.
What is the largest n-digit pandigital prime that exists?

Ring

<lang ring> load "stdlib.ring" see "working..." + nl see "The largest pandigital prime is:" + nl

limit = 7652413

for n = limit to 2 step -2

   flag = 1
   strn = string(n) 
   if isprime(n)
      for m = 1 to len(strn)
          ind = count(strn,strn[m])
          if ind != 1
             flag = 0
          ok
      next
      if flag = 1
         pand = n
         exit
      ok           
   ok

next

see "" + pand + nl

see "done..." + nl

func count(cString,dString)

    sum = 0
    while substr(cString,dString) > 0
          sum++
          cString = substr(cString,substr(cString,dString)+len(string(sum)))
    end
    return sum

</lang>

Output:

The largest pandigital prime is:
9,876,413