What is an ASP Dictionary?
A dictionary is a data structure that stores a collection of name-value pairs in the ASP framework. Each name-value pair maps the name (key) to the corresponding value (item) it is linked to.
Syntax
The following is the syntax used to create a dictionary in ASP. Unlike the declaration of dictionaries found in other programming languages, in ASP, after declaring the variable for the dictionary, you must then set it to a newly created Scripting.Dictionary server object.
Advantage of using dictionaries
The main advantage of using a dictionary over an array is that a dictionary contains built-in properties and methods which allow you to access important information and perform certain functions much quicker than in a typical array.
Methods
These are the functions built into the dictionary data structure. The following are a few of the most common ones and their descriptions:
| Method | Description |
|---|---|
Add |
Allows you to add a new key-item pair in your dictionary |
Exists |
Checks whether a certain key exists in the dictionary. Returns either true or false accordingly |
Items |
Gives you an array of all the items stored in the dictionary |
Keys |
Gives you an array of all the keys stored in the dictionary |
Remove |
Allows you to remove a certain key-item pair entry in the dictionary |
Properties
These are functions that provide data regarding the entries stored in the dictionary or allows you to edit them.
| Properties | Description |
|---|---|
Count |
Tells you the number of entries in the dictionary |
CompareMode |
Allows you to compare keys in a dictionary |
Item |
Can be used to get the item corresponding to a certain key or set this value |
Key |
Used to change the key of an existing entry |
Example
In the following example, we first declare and populate a dictionary. After this, we first check the presence of a key in the dictionary and print out its corresponding item value if present. Next, we remove that key-item pair and once again check for its existence in the dictionary and print out an error message when it is not found.
<%
Dim dict
Set dict=Server.CreateObject("Scripting.Dictionary")
dict.Add "a","apple"
dict.Add "b","ball"
dict.Add "c","cat"
If dict.Exists("a") Then
Response.Write("The value corresponding to the 'a' key is: ", & dict.Item("a"))
Else
Response.Write("Sorry, this entry doesn't exist ")
End If
dict.Remove("a")
If dict.Exists("a") Then
Response.Write("The value corresponding to the 'a' key is: ", & dict.Item("a"))
Else
Response.Write("Sorry, this entry doesn't exist ")
End If
%>
output: The value corresponding to the 'a' key is: apple Sorry, this entry doesn't exist
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