Associative Array (Cross Ref > Data Structures)

Associative Array

Access VBA:   Collection

In addition to Add and Item, collections also offer Count and Remove. Notice that Add uses the format of Value, Key (which is backwards from many other languages).

Dim States As New Collection
   
States.Add "California", "CA"
States.Add "Nevada", "NV"
     
MsgBox (States.Item("CA"))

 Access VBA Associative Array (Collection)

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Code:	Access VBA Associative Array (Collection)
Definition:	Associative Array

ASP Classic:   Scripting.Dictionary

Use the scriptiing dictionary object which is available on later versions of ASP Classic (all still commonly in use).

Note: Both Access VBA and VB Classic use a collection for this but collections are not supported in ASP Classic.

Dim StateList

set StateList = Server.CreateObject("Scripting.Dictionary")
StateList.Add "CA", "California"
StateList.Add "NV", "Nevada"

Response.Write "I live in " & StateList.Item("CA")

 ASP Classic Associative Array (Scripting.Dictionary)

Looping Through An ASP Dictionary

Here's some code that adds a few items to a dictionary and then loops through them using a for each loop.

Dim StateList

Dim Key

  
set StateList = Server.CreateObject("Scripting.Dictionary")
 
StateList.Add "CA", "California"
StateList.Add "NV", "Nevada"
StateList.Add "FL", "Florida"

For Each Key in StateList
  Response.Write Key & " is " & StateList(Key) & "<br>"
Next

Here's one more example showing how to loop through Request.QueryString. Just to show you that you can.

Dim Key

For each Key in Request.QueryString

 Response.Write Key & "=" & Request.QueryString(Key)

Next

Exists and Remove

Use Exists to check if a key is in the associative array and Remove to delete it. It's a good idea to check if an element exists prior to deleting it. Here's how:

If StateList.Exists("FL") Then

    StateList.Remove("FL")

End If

If you fail to check if an element exists and it doesn't, you will get the following error:

Microsoft VBScript runtime  error '800a802b'

Element not found

/path/yourpage.asp, line 51

Sorting

No built-in sort function. However, Microsoft provided a good example of how to do this at http://support.microsoft.com/kb/246067.

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 To/From Code Guide: Associative Array (Cross Ref > Data Structures) vs. Other Languages

Code:	ASP Classic Associative Array (Scripting.Dictionary)
Definition:	Associative Array
FAQ:	Associative Arrays in ASP Classic

C#:   Dictionary

//using System.Collections.Generic;

Dictionary <String, String> airports = new Dictionary <String, String>();
 

airports.Add("LAX", "Los Angeles"); 
airports.Add("SFO", "San Francisco"); 
airports.Add("SAN", "San Diego");
 

MessageBox.Show(airports["LAX"]);

 C# Associative Array (Dictionary)

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Definition:	Associative Array
Code:	C# Associative Array (Dictionary)

C++:   map

map<string, int> mymap;

mymap.insert(AValuePair);

 C++ Associative Array (map)

About Associative Array
A set of unique keys linked to a set of values. Each unique key is associated with a value. Think of it as a two column table. MyArray['CA'] = 'California' MyArray['AR'] = 'Arizona'

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 To/From Code Guide: Associative Array (Cross Ref > Data Structures) vs. Other Languages

Definition:	Associative Array
Code:	C++ Associative Array (map)

Corel Paradox:   DynArray

In ObjectPAL associative arrays are known as dynamic arrays.

var
  myDynArray   DynArray[] String
endVar

myDynArray["Last_Name"] = "Spitz"
myDynArray["First_Name"] = "Randy"

myDynArray.view()

 ObjectPAL Associative Array (DynArray)

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 To/From Code Guide: Associative Array (Cross Ref > Data Structures) vs. Other Languages

Code:	Assocative Arrays in ObjectPAL
Definition:	Associative Array
Code:	ObjectPAL Associative Array (DynArray)

Delphi:   TStringList Assoc Array

Object Pascal doesn't have a native associative array, but you can use a TStringList the same way. (Alternatively, search the Internet for TStringHash and THashedStringList classes for implementations of a true associative array).

Syntax Example: var   StateList : TStringList; begin StateList := TStringList.Create;    StateList.CommaText := 'CA=California, FL=Florida';   ShowMessage('FL is ' + StateList.Values['FL']); end; About Associative Array A set of unique keys linked to a set of values. Each unique key is associated with a value. Think of it as a two column table. MyArray['CA'] = 'California' MyArray['AR'] = 'Arizona' More Info  To/From Code Guide: Associative Array (Cross Ref > Data Structures) vs. Other Languages Definition:  Associative Array Code:  Associative Arrays in Delphi/Object Pascal (Use TStringList)

 Associative Arrays in Delphi/Object Pascal (Use TStringList)

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 To/From Code Guide: Associative Array (Cross Ref > Data Structures) vs. Other Languages

Code:	Assocative Arrays in ObjectPAL
Definition:	Associative Array
FAQ:	Associative Arrays in ASP Classic
Tip:	Associative Arrays in Delphi/Object Pascal
Code:	Associative Arrays in JavaScript

Java:   HashMap()

An associative array links a set of keys to a set of values. In Java, associative arrays are implemented as Maps.

This will print "Arizona."

Syntax Example: import java.util.*; public class Maps {     public static void main(String[] args)     {         Map states = new HashMap();                 states.put("CA", "California");         states.put("FL", "Florida");         states.put("AZ", "Arizona");         System.out.println(states.get("AZ"));     } } About Associative Array A set of unique keys linked to a set of values. Each unique key is associated with a value. Think of it as a two column table. MyArray['CA'] = 'California' MyArray['AR'] = 'Arizona' More Info  To/From Code Guide: Associative Array (Cross Ref > Data Structures) vs. Other Languages Definition:  Associative Array Code:  Associative Arrays in Java (a Map)

 Associative Arrays in Java (a Map)

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 To/From Code Guide: Associative Array (Cross Ref > Data Structures) vs. Other Languages

Code:	Assocative Arrays in ObjectPAL
Definition:	Associative Array
FAQ:	Associative Arrays in ASP Classic
Tip:	Associative Arrays in Delphi/Object Pascal
Code:	Associative Arrays in Delphi/Object Pascal (Use TStringList)

JavaScript:   Array(), use [

Syntax Example: var MyStateList= new Array() MyStateList["CA"]="California"; MyStateList["OR"]="Oregon"; Alert("OR is " + MyStateList["OR"]) About Associative Array A set of unique keys linked to a set of values. Each unique key is associated with a value. Think of it as a two column table. MyArray['CA'] = 'California' MyArray['AR'] = 'Arizona' More Info  To/From Code Guide: Associative Array (Cross Ref > Data Structures) vs. Other Languages Definition:  Associative Array Code:  Associative Arrays in JavaScript

 Associative Arrays in JavaScript

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 To/From Code Guide: Associative Array (Cross Ref > Data Structures) vs. Other Languages

Code:	Assocative Arrays in ObjectPAL
Definition:	Associative Array
FAQ:	Associative Arrays in ASP Classic
Tip:	Associative Arrays in Delphi/Object Pascal
Code:	Associative Arrays in Delphi/Object Pascal (Use TStringList)

Perl:   % Array Preface

my %weekdays = (
'Sun' => 'Sunday',
'Mon' => 'Monday',
'Tue' => 'Tuesday',
'Wed' => 'Wednesday',
'Thu' => 'Thursday',
'Fri' => 'Friday',
'Sat' => 'Saturday',
);

my $day_of_the_week = $weekdays{'Mon'};

 Perl Associative Array (% Array Preface)

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 To/From Code Guide: Associative Array (Cross Ref > Data Structures) vs. Other Languages

Definition:	Associative Array
Code:	Perl Associative Array (% Array Preface)

PHP: 

Declare associative array with initial known values. You can also add to associative array. (You can just assign values without ever declaring it too!)

$prices = array( 'Tires'=>100, 'Spark Plugs'=>4 );
$prices['Oil'] = 10;

echo "Tires=" . $prices['Tires'] . "<br>";
echo "Oil=" . $prices['Oil'] . "<br>";

 PHP Associative Array

About Associative Array
A set of unique keys linked to a set of values. Each unique key is associated with a value. Think of it as a two column table. MyArray['CA'] = 'California' MyArray['AR'] = 'Arizona'

Complete Example

Here is a complete example:

<html>

<head><title>PHP Hello World Example</title></head>

<body>
 

<?PHP
//Declare associative array with initial known values.
$prices = array( 'Tires'=>100, 'Spark Plugs'=>4 );

//Add to associative array. (You can just assign values without ever declaring it too!)
$prices['Oil'] = 10;

//Usage Example 1
echo "<br><br>Example 1<br>";
echo "Tires=" . $prices['Tires'] . "<br>";
echo "Oil=" . $prices['Oil'] . "<br>";

//Usage Example 2 - foreach loop with $key and $value
echo "<br><br>foreach loop<br>";

foreach ($prices as $key => $value)
 echo $key.'=>'.$value.'<br />';

//
//Clear it for another use.
//
echo "<br><br>reset example<br>";
reset($prices);

$prices['Computer'] = 700;
$prices['monitor'] = 200;
$prices['mouse'] = 15;

foreach ($prices as $key => $value)
  echo $key.'=>'.$value.'<br />';
?>

 
</body>

</html>

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 To/From Code Guide: Associative Array (Cross Ref > Data Structures) vs. Other Languages

Definition:	Associative Array
Code:	PHP Associative Array

VB Classic:   Collection

In addition to Add and Item, collections also offer Count and Remove. Notice that Add uses the format of Value, Key (which is backwards from many other languages).

Dim States As New Collection
   
States.Add "California", "CA"
States.Add "Nevada", "NV"
     
MsgBox (States.Item("CA"))

 VB Classic Associative Array (Collection)

More Info

 To/From Code Guide: Associative Array (Cross Ref > Data Structures) vs. Other Languages

Definition:	Associative Array
Code:	VB Classic Associative Array (Collection)

VB.Net:   Dictionary

An associative array links a set of keys to a set of values. In Visual Basic, associative arrays are implemented as Dictionaries.

This code produces a message box saying "Nevada."

Syntax Example: //Imports System.Collections.Generic � Dim States As New Dictionary(Of String, String) States.Add("CA", "California") States.Add("NV", "Nevada") MsgBox(States("NV")) About Associative Array A set of unique keys linked to a set of values. Each unique key is associated with a value. Think of it as a two column table. MyArray['CA'] = 'California' MyArray['AR'] = 'Arizona' Linked Certification Question(s) The following are practice certification questions with answers highlighted. These questions were prepared by Mike Prestwood and are intended to stress an important aspect of this KB post. All our practice questions are intended to prepare you generally for passing any certification test as well as prepare you for professional work. Intermediate 1 Intermediate Level Question Question #1: Multiple Choice Which code snippet is the correct syntax for declaring and using an associative array? Answer: 1.  //Imports System.Collections.Generic Dim States As New Collection States.Add("CA", "California") States.Add("NV", "Nevada") MsgBox(States("NV")) 2.  //Imports System.Collections.Generic Dim States As New _ Dictionary(Of String, String) States.Add("CA", "California") States.Add("NV", "Nevada") MsgBox(States("NV")) 3.  //Imports System.Collections.Generic Dim States As New _ Collection(Of String, String) States("CA") = "California" States("NV") = "Nevada" MsgBox(States.Item("NV")) 4.  //Imports System.Collections.Generic Dim States As New Collection(Of String) States.Add("CA", "California") States.Add("NV", "Nevada") MsgBox(States.Item("NV")) 5.  //Imports System.Collections.Generic Dim States As New Array(String, String) States.Add("California", "CA") States.Add("Nevada", "NV") MsgBox(States.ListItem("NV")) More Info  To/From Code Guide: Associative Array (Cross Ref > Data Structures) vs. Other Languages Definition:  Associative Array Code:  Associative Arrays in Visual Basic (a Dictionary)

 Associative Arrays in Visual Basic (a Dictionary)

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 To/From Code Guide: Associative Array (Cross Ref > Data Structures) vs. Other Languages

Code:	Assocative Arrays in ObjectPAL
Definition:	Associative Array
FAQ:	Associative Arrays in ASP Classic
Tip:	Associative Arrays in Delphi/Object Pascal
Code:	Associative Arrays in Delphi/Object Pascal (Use TStringList)