![]() The code creates a new object called ‘M圜ollection’ and then the following lines of code use the Add method to add in 3 new values. Global M圜ollection As New Collection Create a Collection, Add Items, and Access ItemsĪ simple collection object can be created in VBA using the following code: Sub CreateCollection() If you want any module within your workbook to access the collection, then define it as a global object. ![]() This will ensure that all your code within that module can access the collection. If you want your collection to be available to all the code in your code module, then you need to declare the collection object in the Declare section at the top of the module window. If the workbook is re-opened then the collection needs to be re-created using VBA code. It does not get saved when the workbook is saved. In terms of scope, the collection object is only available whilst the workbook is open. It just grows and shrinks automatically as items are added or removed. A collection size does not need to be defined. If you need to increase the size of the array you can use ‘ReDim’ to re-size it, but you need to use the keyword ‘Preserve’ if you do not want to lose the data already held in the array. You need to have an idea of how much data it is going to store. The size of an array needs to be defined when it is first created.Arrays do not have this function and require looping code to iterate through the array to find specific values. Collections can use keys to locate data.In coding terms, when you create a collection object, it only has two methods (Add and Remove) and two properties (Count and Item), so the object is by no means complicated to program. Collections are generally easier to use than arrays.If you tried to put a string value in an array that was dimensioned as numeric, it would produce an error message. You could have a numeric value, a date, or a string – the collection object will take any data type. In a collection, you can add use data types of data for each item. You could have a very complicated array structure using a custom data type which in turn has several custom data types below it. However, in the array you can use custom data types that you have designed yourself. In an array, you can only use a single data type for the elements which is set when you dimension the array.With a collection, you would have to remove the value to be changed first and then add in the new changed value. Collections are Read Only whereas array values can be changed using VBA.Arrays are useful for a fixed size of data, but collections are better for where the quantity of data is liable to change. ![]() The item that has been removed disappears completely. In a collection you use the Add or Remove methods, and all the indexing and re-sizing is automatically taken care of. If you are using a For Next loop to iterate through the array, the loop will return a blank value, which will need coding to make sure that the blank value is ignored. You can set the values of an element to a blank value, but the element itself still exists within the array.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |