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If you've worked with arrays in the C programming language, or even read about working with them in C, you might regard an array as a tabular structure used to hold data, much like a spreadsheet table with clearly defined limits and dimension. A 2-dimensional (2D) array would be like a simple table; a 3-dimensional array would be like a cube made up of individual cells.
ColdFusion arrays aren't quite that simple because they are dynamic. So in a 2D array, for example, you might have what you could think of as columns of differing lengths based on the data that has been added or removed, whereas in a conventional array, array size is constant and symmetrical.
In ColdFusion, you declare an array by assigning a variable name to the new array as follows:
<CFSET mynewarray=ArrayNew(x)>
where x is the number of dimensions (from 1 to 3) in the array you want to create. You can visualize a one-dimensional (1D) array as a string of cells, like a single row from a table.
Once created, you can add data to the array, in this case using a form variable:
<CFSET mynewarray[3]=Form.emailaddress>
Data in an array is referenced by index number, in the following manner:
#My1DArray[index1]#<BR> #My2DArray[index1][index2]#<BR> #My3DArray[index1][index2][index3]#
The following terms will help you understand subsequent discussions of ColdFusion arrays:
The syntax my2darray[1][3]="Paul"
is the same as saying `My2dArray is a two dimensional array and the value of the array element index [1][3] is "Paul".'
Dynamic arrays expand to accept data you add to them and contract as you remove data from them. This diagram shows the difference between a static 2D array and a ColdFusion dynamic 2D array.
A ColdFusion 2D array is actually a 1D array that contains a series of additional 1D arrays. Each of the arrays that make up a column can expand and contract independently of any other column.
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