STATEMENT:  ReDim
ReDim
 
The ReDim statement allows you to formally declare, and to later redeclare as many times as you need, the size (and hence the memory space allocation) for a dynamic array that was originally declared using either a Dim, Private or Public statement.
 
The first time you use ReDim to declare an array, you can create either a single or a multiple dimension array. However, after you have set the number of the dimensions, you cannot later go back and change the number of the dimensions. Also, once you have created a multi-dimension array, you can only redeclare the size of the last element.
 
If you make the array bigger, you can use the keyword Preserve to protect all of the existing elements. If you make the array smaller, you will lose part of the array elements even if you use Preserve. Do not use Preserve the first time that you ReDim an array since it will prohibit setting multiple dimensions.
 
In this example, we declare myarray() to have a single dimensions and then resize the element. When we resize from 999 down to 9, we lose the data in the other 990 elements.
 
Code:
<% Dim myarray() %>
<% ReDim myarray(5) %>
<% ReDim Preserve myarray(999) %>
<% ReDim Preserve myarray(9) %>
 
In this example, we declare myarray() to have three dimensions and then resize the last element. When we resize the last element from 999 down to 9, we lose the data in the other 990 elements.
 
Code:
<% Dim myarray() %>
<% ReDim myarray(20, 10, 99) %>
<% ReDim Preserve myarray(20, 10, 999) %>
<% ReDim Preserve myarray(20, 10, 9) %>