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{{Template:Arraylist:FindPreviousItemNumber subtitle}}
{{Template:Arraylist:FindPreviousItemNumber subtitle}}
<var>FindPreviousItemNumber</var> searches "backward" in the <var>Arraylist</var> to find and return the item number of the previous item that matches a specified criterion.  The criterion is supplied by the <var>[[SelectionCriterion class|SelectionCriterion]]</var> object that is a required <var>FindPreviousItemNumber</var> parameter. If no item satisfies the criterion, the method returns a zero.


This function searches "backward" in the <var>Arraylist</var> to find and return
the item number of the next item that matches a specified criterion.
The criterion is supplied by the [[SelectionCriterion class|SelectionCriterion]] object
that is a required <var>FindPreviousItemNumber</var> parameter.
If no item satisfies the criterion,
the method returns a zero.
<var>FindPreviousItemNumber</var> is available in ''Sirius Mods'' version 7.6 and later.
==Syntax==
==Syntax==
{{Template:Arraylist:FindPreviousItemNumber syntax}}
{{Template:Arraylist:FindPreviousItemNumber syntax}}
===Syntax terms===
===Syntax terms===
<table class="syntaxTable">
<table class="syntaxTable">
<tr><th>%itemnum</th>
<tr><th>%number</th>
<td>A numeric variable to contain the item number of the item that is located by the search. </td></tr>
<td>A numeric variable to return the item number of the item that is located by the search. </td></tr>
 
<tr><th>al</th>
<tr><th>al</th>
<td>An <var>Arraylist</var> object. </td></tr>
<td>An <var>Arraylist</var> object. </td></tr>
<tr><th><i>criterion</i></th>
 
<td>A <var>SelectionCriterion</var> object, which is a relational expression that is applied to an ''<var class="term">al</var>'' item value to determine whether the value satisfies the expression. The expression consists of a function, an operator, and a numeric or string value.
<tr><th>selectionCriterion</th>
For example, <code>GT(this, -11)</code> is the criterion <code>this > -11</code>, where <code>this</code> is an identity function that simply returns the item's value. The item number of the first item tested by <var>FindPreviousItemNumber</var> that satisfies this expression is the method's return value.
<td>A <var>SelectionCriterion</var> object, which is a relational expression that is applied to an <var class="term">al</var> item value to determine whether the value satisfies the expression. The expression consists of a function, an operator, and a numeric or string 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 ''<var class="term">al</var>'' declaration and that returns a numeric or string value. This is described further in [[SelectionCriterion class#Specifying a SelectionCriterion's parameters|Specifying a SelectionCriterion's parameters]].</td></tr>
<p>
<tr><th>Start</th>
For example, <code>GT(this, -11)</code> is the criterion <code>this > -11</code>, where <var class="term">this</var> is an identity function that simply returns the item's value. The item number of the first item tested by <var>FindPreviousItemNumber</var> that satisfies this expression is the method's return value.</p>
<td>The number of the item ''before'' which to begin the search. If the ''itemnum'' value of Start is 4, item 3 is the first item considered. The value of Start may be 1 through one plus the number of items in the <var>Arraylist</var>. For a collection of three items, ''itemnum'' may be 1, 2, 3, or 4.
<p>
This is an optional argument, and it defaults to one plus the number of items in the collection. If you specify a value, the parameter name <var>Start</var> is required.</td></tr>
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 <var class="term">al</var> declaration and that returns a numeric or string value. This is described further in [[SelectionCriterion class#Specifying a SelectionCriterion's parameters|"Specifying a SelectionCriterion's parameters"]].</p></td></tr>
 
<tr><th><var>Start</var></th>
<td>The number of the item <b><i>before</i></b> which to begin the search. If the <var class="term">number</var> value of <var>Start</var> is 4, item 3 is the first item considered. The value of <var>Start</var> may be 1 through the number of items in the <var>Arraylist</var> plus one. For a collection of three items, <var class="term">number</var> may be 1, 2, 3, or 4.
<p>
The default value for <var>Start</var> is the number of items in the collection plus one; to start from the last item in <var class="term">al</var>.</p>
<p>
This is an optional, [[Notation conventions for methods#Named parameters|name required]], argument; if you specify a value, the parameter name <var>Start</var> is required.</p></td></tr>
</table>
</table>


==Usage notes==
==Usage notes==
<ul>
<ul>
<li>If the value of Start is not in the range of 2 through one plus the number
<li>If the value of <var>Start</var> is not in the range of 2 through one plus the number of items in the <var>Arraylist</var>, the request is cancelled. If the value of <var>Start</var> is 1, no item can be found and <var>FindPreviousItemNumber</var> returns a zero.
of items in the <var>Arraylist</var>, the request is cancelled.
 
If the value of Start is 1, no item can be found and
<li><var>FindPreviousItemNumber</var> is available in <var class="product">[[Sirius Mods|Sirius Mods]]</var> Version 7.6 and later.
the method returns a zero.
<li>[[FindNextItemNumber (Arraylist function)|FindNextItemNumber]]
is identical to <var>FindPreviousItemNumber</var> except that it searches forward in the <var>Arraylist</var>.
</ul>
</ul>
==Examples==
==Examples==
The following request contains two <var>FindPreviousItemNumber</var> calls: the first, for an <var>Arraylist</var> of strings, starts checking the last item first, by default; the second call, for an <var>Arraylist</var> of float, uses a compound criterion:
<p class="code">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 class|SelectionCriterion]] for string len 10
  %sel2 is object selectioncriterion for float
  %sel = LT(this, 'boston')
  %sel2 = OR(GT(this, 100), LT(this, 0))
 
  [[PrintText statement|printText]] {~} is: {%al:findPreviousItemNumber(%sel)}
  printtext {~} is: {%al2:findPreviousItemNumber(%sel2, start=6)}
end
</p>
The result is:
<p class="output">%al:findPreviousItemNumber(%sel) is: 4
%al2:findPreviousItemNumber(%sel2, start=6) is: 1
</p>


The following request contains two <var>FindPreviousItemNumber</var> calls: the first, for
an <var>Arraylist</var> of strings, starts checking the last item first, by default;
the second call, for an <var>Arraylist</var> of float, uses a compound criterion:
<pre style="xmp">
    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
</pre>
The result is:
<pre style="xmp">
    %al:findPreviousItemNumber(%sel) is: 4
    %al2:findPreviousItemNumber(%sel2, start=6) is: 1
</pre>
==See also==
==See also==
<ul><li><var>[[FindNextItemNumber (Arraylist function)|FindNextItemNumber]]</var> is identical to <var>FindPreviousItemNumber</var> except that it searches forward in the <var>Arraylist</var>.</ul>
{{Template:Arraylist:FindPreviousItemNumber footer}}
{{Template:Arraylist:FindPreviousItemNumber footer}}

Latest revision as of 23:35, 9 August 2012

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.

Syntax

%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.

Examples

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.