ListOffsetBefore
Type
operator
Summary
Find the first or last occurrence of Needle within the head of Haystack Target:An expression which evaluates to a List.
Syntax
the ( first | last ) offset of <Needle> before <Before> in <Haystack>
Description
Use the offset of⦠before to find where a particular sub-list occurs
within a list. Haystack is scanned for a sequence of elements that
are equal to the elements of Needle, stopping before the position
Before, and the position of the start of the sequence found is
returned. If no sub-list of Haystack before the position Before
is equal to Needle, the return value is 0. If neither "first" nor
"last" is specified, the last matching subsequence is found.
Parameters
| Name | Type | Description |
|---|---|---|
Needle | An expression which evaluates to List. | |
Before | An expression which evaluates to a valid index in Target. |
Examples
variable tVar as List
variable tOffset as Number
put ["a", "b", "c", "d", "b","c"]
put the offset of ["b","c"] before 5 in tVar into tOffset
--tOffset contains 2
put the first offset of ["b","c"] before 6 in tVar into tOffset
--tOffset contains 2