'MODULUS - check for valid Credit card nr - may still be invalid card due
'          to theft etc


external  fentrybox() Background()

public    ptstr

global    x $cardnr CalcEven() CalcOdd()


MAIN
  Background()                         ' enter nr - mask to batches of 4
  while true
    x = fentrybox(" Enter Card Number ",19,"*4#\-*4#\-*4#\-*4#","")
    if x = -1
      continue while
    end if
    $cardnr =str(left(ptstr,4))|str(mid(ptstr,6,4))|str(mid(ptstr,11,4))|str(mid(ptstr,16,4))'message "$cardnr is:"&str($cardnr)
    exit while
  end while

' check whether ODD or even digits

' calculate
  CalcEven()
' display issuer of card & whether correct


END MAIN


Function CalcEven()
local l i nr
message "$cardnr is:"&str($cardnr)
  l=len($cardnr)
  for i = 0 to l-1
    nr=mid($cardnr,l-i,1)
message "nr is:"&str(nr)
  end for
End Function 'CalcEven()


Function CalcOdd()


End Function 'CalcOdd()