Mastering the ReDim Statement in Excel VBA: Redefine Arrays with Ease

In this video, you will learn about the ReDim statement in Excel VBA, which allows you to redefine or re-declare arrays. You will see practical examples of how to use the ReDim statement to adjust the size of an array dynamically. Additionally, you will understand the importance of the `Preserve` keyword in maintaining existing data within an array when its size is changed.

What will you learn

• How to use the ReDim statement to redefine arrays in Excel VBA.
• The purpose and syntax of the ReDim statement.
• Practical examples of using ReDim to change array size.
• The functionality of the `Preserve` keyword.
• How `Preserve` helps in maintaining existing array data during resizing.
• Writing and running loops to fill and print arrays in VBA.

Takeaway notes

• The `Dim` statement is used to define a dimension or declare an array in VBA.
• The `ReDim` statement can change the size of an existing array.
• Use the `Preserve` keyword with `ReDim` to keep existing data in the array while resizing.
• Without `Preserve`, all existing data in the array will be lost when the array is resized.
• Use loops to fill and process arrays in VBA.
• The `Ubound` function can be used to determine the upper boundary of an array.

Practice questions

1. What is the purpose of the `Dim` statement in VBA?
2. How does the `ReDim` statement differ from the `Dim` statement?
3. Write a VBA code snippet to declare an empty array and then resize it using the `ReDim` statement.
4. How can you ensure that data in an array is not lost when resizing it using `ReDim`?
5. Write a VBA script where you initially define an array of size 3, populate it, and then resize it to size 6 while preserving the original data.
6. What will happen if you try to resize an array with `ReDim` without using `Preserve`?
7. Explain the purpose of the `Preserve` keyword in your own words.
8. Demonstrate using a loop to fill an array with values after resizing it in VBA.
9. Write a VBA code snippet to print all the values of an array after resizing it.
10. How can the `Ubound` function be helpful when working with arrays?
11. What are the steps to redefine an array in VBA to a larger size while preserving its initial values?
12. Explain how you would handle an array if its new size is smaller than the current size.
13. What would you do to completely clear all elements of an array and then redefine its size in VBA?
14. Describe a scenario in which dynamically resizing an array would be useful in an Excel VBA project.
15. Provide an example of resizing an array multiple times and explain how each step maintains data integrity.