How to Determine the Length of an Array in VBA in 3 Minutes (Excel)

Written by Kasper Langmann

Determining the length of an array in Visual Basic for Applications (VBA) is a fundamental skill for anyone looking to manipulate data in Excel. Whether you’re a seasoned programmer or a beginner, this guide will provide you with the knowledge you need to quickly and accurately find the length of an array in VBA.

Understanding Arrays in VBA

Before we delve into how to determine the length of an array, it’s essential to understand what an array is. In VBA, an array is a type of variable that can store multiple values. These values can be of the same type, such as integers, or different types, such as strings and dates. The values in an array are stored in a specific order, and each value has an index number that indicates its position in the array.

Arrays in VBA can be either static or dynamic. A static array has a fixed size, which is determined when the array is declared. On the other hand, a dynamic array can change size during the execution of the program, allowing for greater flexibility.

Static Arrays

When declaring a static array in VBA, you must specify the number of elements it will contain. This number becomes the upper bound of the array. For example, if you declare an array with five elements, the upper bound of the array is four, as the index starts at zero.

Here is an example of how to declare a static array in VBA:

Dim myArray(4) As Integer

Dynamic Arrays

Dynamic arrays in VBA are declared without specifying the number of elements they will contain. Instead, you use the ReDim statement to set the size of the array at runtime. This allows you to adjust the size of the array as needed, adding or removing elements as your program requires.

Here is an example of how to declare a dynamic array in VBA:

Dim myArray() As Integer
ReDim myArray(4)

Determining the Length of an Array in VBA

Now that we understand what arrays are and how they’re declared in VBA, we can move on to determining their length. The length of an array refers to the number of elements it contains. In VBA, you can find this number by using the UBound function.

The UBound function returns the upper bound of an array, which is the highest index number. Since the index of an array starts at zero, the upper bound is one less than the number of elements in the array. Therefore, to get the length of an array, you add one to the result of the UBound function.

Here is an example of how to use the UBound function to find the length of an array:

Dim myArray(4) As Integer
Dim arrayLength As Integer
arrayLength = UBound(myArray) + 1

Working with Multi-Dimensional Arrays

In VBA, you can also work with multi-dimensional arrays. These are arrays that have more than one dimension, or index. For example, a two-dimensional array has two indices, one for rows and one for columns.

To find the length of a multi-dimensional array, you use the UBound function with an additional argument that specifies the dimension you’re interested in. The first dimension is 1, the second dimension is 2, and so on.

Here is an example of how to find the length of a two-dimensional array:

Dim myArray(4, 2) As Integer
Dim arrayLength As Integer
arrayLength = UBound(myArray, 1) + 1

Common Mistakes and Troubleshooting

While the process of determining the length of an array in VBA is straightforward, there are common mistakes that can lead to errors or incorrect results. One of these mistakes is forgetting that the index of an array starts at zero. This can lead to off-by-one errors, where you’re either missing the last element of the array or trying to access an element that doesn’t exist.

Another common mistake is trying to use the UBound function on an array that hasn’t been initialized. If you declare a dynamic array but don’t use the ReDim statement to set its size, the UBound function will return an error. To avoid this, always make sure your array has been properly initialized before trying to find its length.

Finally, when working with multi-dimensional arrays, remember that the UBound function only returns the upper bound of the specified dimension. If you want to find the total number of elements in the array, you’ll need to multiply the lengths of all dimensions.

Conclusion

Determining the length of an array in VBA is a simple but crucial task for any programmer working with Excel. By understanding how arrays work and how to use the UBound function, you can easily find the length of any array, whether it’s static or dynamic, one-dimensional or multi-dimensional. Remember to avoid common mistakes and always ensure your arrays are properly initialized to prevent errors and achieve accurate results.