Tech Tip: Utility method to get the last position of substring

PRODUCT: 4D | VERSION: 19 | PLATFORM: Mac & Win

Published On: August 1, 2022

The method below returns the position of the last occurrence of a substring. If the substring is not found, the method returns 0 (zero).

// Method: lastPosition
#DECLARE($target : Text; $source : Text)->$lastPos : Integer
var $revSrc; $revTgt : Text
var $revPos : Integer

If (Count parameters=2)
   $revSrc:=Split string($source; "").reverse().join("")
   $revTgt:=Split string($target; "").reverse().join("")
   $revPos:=Position($revTgt; $revSrc; *)
   If ($revPos>0)
     $lastPos:=Length($source)-Length($target)-$revPos+2
   End if
Else
   $lastPos:=0
End if

Examples:

$pos:=lastPosition("oo"; "poolroom") // Returns 6

$pos:=lastPosition("tr"; "website") // Returns 0