
Contents > Developing ColdFusion MX Applications > Using Arrays and Structures > Basic array techniques > Creating arrays Creating complex multidimensional arrays

Creating complex multidimensional arrays

ColdFusion supports dynamic multidimensional arrays. When you declare an array with the ArrayNew function, you specify the number of dimensions. You can create an asymmetrical array or increase an existing array's dimensions by nesting arrays as array elements.

It is important to know that when you assign one array (array1) to an element of another array (array2), array1 is copied into array2. The original copy of array1 still exists, independent of array2. You can then change the contents of the two arrays independently.

The best way to understand an asymmetrical array is by looking at it. The following example creates an asymmetric, multidimensional array and the cfdump tag displays the resulting array structure. Several array elements do not yet contain data.

<cfset myarray=ArrayNew(1)>
<cfset myotherarray=ArrayNew(2)>
<cfset biggerarray=ArrayNew(3)>

<cfset biggerarray[1][1][1]=myarray>
<cfset biggerarray[1][1][1][10]=3>
<cfset biggerarray[2][1][1]=myotherarray>
<cfset biggerarray[2][1][1][4][2]="five deep">

<cfset biggestarray=ArrayNew(3)>
<cfset biggestarray[3][1][1]=biggerarray>
<cfset biggestarray[3][1][1][2][3][1]="This is complex">
<cfset myarray[3]="Can you see me">

<cfdump var=#biggestarray#><br>
<cfdump var=#myarray#>

Note: The cfdump tag displays the entire contents of an array. It is an excellent tool for debugging arrays and array-handling code.

Reviewing the code

The following table describes the code:

Code	Description
<cfset myarray=ArrayNew(1)> <cfset myotherarray=ArrayNew(2)> <cfset biggerarray=ArrayNew(3)>	Create three empty arrays, a 1D array, a 2D array, and a 3D array.
<cfset biggerarray[1][1][1]=myarray> <cfset biggerarray[1][1][1][10]=3>	Make element [1][1][1] of the 3D biggerarray array be a copy of the 1D array. Assign 3 to the [1][1][1][10] element of the resulting array. The biggerarray array is now asymmetric. For example, it does not have a [1][1][2][1] element.
<cfset biggerarray[2][1][1]= myotherarray> <cfset biggerarray[2][1][1][4][2]= "five deep">	Make element [2][1][1] of the 3D array be the 2D array, and assign the [2][1][1][4][2] element the value "five deep". The biggerarray array is now even more asymmetric.
<cfset biggestarray=ArrayNew(3)> <cfset biggestarray[3][1][1] =biggerarray> <cfset biggestarray[3][1][1][2][3][1] ="This is complex">	Create a second 3D array. Make the [3][1][1] element of this array be a copy of the bigerarray array, and assign element [3][1][1][2][3][1]. The resulting array is very complex and asymmetric.
<cfset myarray[3]="Can you see me">	Assign a value to element [3] of myarray.
<cfdump var=#biggestarray#><br> <cfdump var=#myarray#>	Use `cfdump` to view the structure of biggestarray and myarray. Notice that the "Can you see me" entry appears in myarray, but not in biggestarray, because biggestarray has a copy of the original myarray values and is not affected by the change to myarray.


Contents > Developing ColdFusion MX Applications > Using Arrays and Structures > Basic array techniques > Creating arrays Creating complex multidimensional arrays

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