$pos
From Scriptwiki
Returns a number indicating the position of the Nth occurrence of string in text.
$pos(text,string,N)
If N is zero, it returns the number of times string appears in text.
Note: You can use $poscs() for a case-sensitive version.
Example
$pos(hello there,e,1) returns 2
$pos(hello there,e,2) returns 9
$pos(hello there,a,1) returns $null