FindPreviousItemNumber (Arraylist function)

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Return number of matching item (Arraylist class)

FindPreviousItemNumber searches "backward" in the Arraylist to find and return the item number of the previous item that matches a specified criterion. The criterion is supplied by the SelectionCriterion object that is a required FindPreviousItemNumber parameter. If no item satisfies the criterion, the method returns a zero.


%number = al:FindPreviousItemNumber( selectionCriterion, [Start= number])

Syntax terms

%number A numeric variable to return the item number of the item that is located by the search.
al An Arraylist object.
selectionCriterion A SelectionCriterion object, which is a relational expression that is applied to an al item value to determine whether the value satisfies the expression. The expression consists of a function, an operator, and a numeric or string value.

For example, GT(this, -11) is the criterion this > -11, where this is an identity function that simply returns the item's value. The item number of the first item tested by FindPreviousItemNumber that satisfies this expression is the method's return value.

The function in the criterion is a method value (a method or class member name literal, or a method variable) for a method that operates on items of the type specified on the al declaration and that returns a numeric or string value. This is described further in "Specifying a SelectionCriterion's parameters".

Start The number of the item before which to begin the search. If the number value of Start is 4, item 3 is the first item considered. The value of Start may be 1 through the number of items in the Arraylist plus one. For a collection of three items, number may be 1, 2, 3, or 4.

The default value for Start is the number of items in the collection plus one; to start from the last item in al.

This is an optional, name required, argument; if you specify a value, the parameter name Start is required.

Usage notes

  • If the value of Start is not in the range of 2 through one plus the number of items in the Arraylist, the request is cancelled. If the value of Start is 1, no item can be found and FindPreviousItemNumber returns a zero.
  • FindPreviousItemNumber is available in Sirius Mods Version 7.6 and later.


The following request contains two FindPreviousItemNumber calls: the first, for an Arraylist of strings, starts checking the last item first, by default; the second call, for an Arraylist of float, uses a compound criterion:

begin %al is arraylist of string len 10 %al2 is arraylist of float %al = list('boston', 'belmont', 'brighton', - 'bedford', 'boxford') %al2 = list(111, 29, 0, 93, 77, -345) %sel is object SelectionCriterion for string len 10 %sel2 is object selectioncriterion for float %sel = LT(this, 'boston') %sel2 = OR(GT(this, 100), LT(this, 0)) printText {~} is: {%al:findPreviousItemNumber(%sel)} printtext {~} is: {%al2:findPreviousItemNumber(%sel2, start=6)} end

The result is:

%al:findPreviousItemNumber(%sel) is: 4 %al2:findPreviousItemNumber(%sel2, start=6) is: 1

See also

  • FindNextItemNumber is identical to FindPreviousItemNumber except that it searches forward in the Arraylist.