First some general information about how arrays behave in Coldfusion as compared to other programming languages.

• Arrays can have numeric indexes only (if you want to have a string index use structs instead)
• Arrays begin at index [1]
• Arrays can have one ore more dimensions

Creating arrays explicitly using ArrayNew()

Declare an array with the ArrayNew function. Specify the number of dimensions as an argument.

• ArrayNew(dimension) creates an array of 1–3 dimensions.
• ColdFusion arrays expand dynamically as data is added.
• ArrayNew() returns an array.

History

Introduced in ColdFusion MX 6

Declaration

CFML

<!--- One Dimension Array--->
<cfset oneDimensionArray = ArrayNew(1)>

CFScript Note that inside a function you should use var scoping. Earlier versions of CF required var scoping to be the first thing in a function; later versions allow it anywhere in a function.

<cfscript>
    oneDimensionArray = ArrayNew(1);

    public void function myFunc() { 
        var oneDimensionArray = ArrayNew(1);
    } 
</cfscript>

After creating the array, add elements by using the element indexes. The Coldfusion Array index starts from 1:

CFML

<cfset oneDimensionArray[1] = 1>
<cfset oneDimensionArray[2] = 'one'>
<cfset oneDimensionArray[3] = '1'>

CFScript

<cfscript>
    oneDimensionArray[1] = 1;
    oneDimensionArray[2] = 'one';
    oneDimensionArray[3] = '1';
</cfscript>

Using ArrayAppend()

You can add elements to an array using the function ArrayAppend(array, value).

<cfscript>
    ArrayAppend(oneDimensionArray, 1);
    ArrayAppend(oneDimensionArray, 'one');
    ArrayAppend(oneDimensionArray, '1');
</cfscript>

Output the array contents using <cfdump>:

<cfdump var="#oneDimensionArray#">

Results:

CFML

<!--- Two Dimension Array--->
<cfset twoDimensionArray = ArrayNew(2)>
<cfset twoDimensionArray[1][1] = 1>
<cfset twoDimensionArray[1][2] = 2>
<cfset twoDimensionArray[2][1] = 3>
<cfset twoDimensionArray[2][2] = 4>

CFScript

<cfscript>
    twoDimensionArray = ArrayNew(2);
    
    twoDimensionArray[1][1] = 1;
    twoDimensionArray[1][2] = 2;
    twoDimensionArray[2][1] = 3;
    twoDimensionArray[2][2] = 4;
</cfscript>

Outputting the contents of array using <cfdump>

<cfdump var="#twoDimensionArray#">

Result:

Each element contains another Array, which will store the values.

Creating 1-D Array Implicitly

When creating an array implicitly, brackets ([]) surround the array contents with comma separators.

<cfset oneDimensionArrayImplicit = [ 1 ,'one','1' ]>

This statement is equivalent to the four statements used to create the above oneDimensionArray. The result are the same when using:

<cfdump var="#oneDimensionArrayImplicit#">

Create 2-D Array Implicitly

<cfset twoDimensionArrayImplicit = [[ 1 , 2 ],[ 3 , 4 ],[ 5 , 6 ]]>

Or:

<cfset firstElement = ["1", "2"]> 
<cfset secondElement= ["3", "4"]> 
<cfset thirdElement = ["5", "6"]> 
<cfset twoDimensionArrayImplicit = [firstElement , secondElement, thirdElement]>

Outputting the content using

<cfdump var="#twoDimensionArrayImplicit#">

Alternative Explicit Declaration

Also you can declare 1 Dimension Array as

<cfset oneDimensionArray = []>

<cfscript>
    oneDimensionArray = [];
</cfscript>

This declaration is same as that of using ArrayNew(1).

But if you try declaring 2 Dimension Array as

<cfset twoDimensionArray =[][]>    //Invalid CFML construct

an error will occur while processing this request.

Following statement will process the request:

<cfset twoDimensionArray =[]>

but variable twoDimensionArray will not actually an Array within Array (or 2-Dimension Array). It actually contains structure within Array.

<cfset twoDimensionArray =[]>
<cfset twoDimensionArray[1][1] = 1>
<cfset twoDimensionArray[1][2] = 2>
<cfset twoDimensionArray[2][1] = 3>
<cfset twoDimensionArray[2][2] = 4>

<cfdump var="#twoDimensionArray#">

Result:

<cfscript>
    oneDimensionArray = ArrayNew(1);
    oneDimensionArray[1] = 1;
    oneDimensionArray[2] = 'one';
    oneDimensionArray[3] = '1';
</cfscript>

<cfif IsDefined("oneDimensionArray")>
    <cfdump var="#oneDimensionArray#">
</cfif>

Result:

Also, we can declare an one Dimension Array as:

oneDimensionArray = [];

Alternatively, CF introduced WriteDump() from CF9 as a function equivalent to the <cfdump> tag which can be used in <cfscript>.

<cfscript>
    WriteDump(oneDimensionArray);
</cfscript>

Similarly, for 2 Dimension Array:

<cfscript>
    twoDimensionArray = ArrayNew(2);
    twoDimensionArray[1][1] = 1;
    twoDimensionArray[1][2] = 2;
    twoDimensionArray[2][1] = 3;
    twoDimensionArray[2][2] = 4;
</cfscript>
<cfdump var="#twoDimensionArray#">

Result: