An enumeration is a list of integer values, each one mapped to a name.
Let us consider an example in which we have to store a category into a Class. Let us also assume that the Class name is AccoutClass and categories are creditor, debtor, bank and general. Instead of using literals to describe the various categories, we will use an enumeration with the following names.
The above statements must appear outside any procedure we use in the class. We will place them at the beginning of the file, right after the declaration of the Class.
In our example, the name Creditor corresponds to 1, the name Debtor corresponds to 2, and so on. Notice that we use enumerations to replace numeric constants with more meaningful names, in this case AccountCategory. We will see how enumerations are used both in the class and the calling application. The below code shows how enumerations are used in the calling software application program.
In the above code, we check whether the user has selected an account, and then assign AccountCategory enumerator member - Creditor or Debtor, to a variable AccountCat of the AccForm.
As we can see, the members of the AccountCategory enumeration become properties of the enumerator.
The advantage of using enumerations is that we can manipulate meaningful names instead of numeric constants. This makes your vb code less prone to errors and far easier to understand.
Note that the members of an enumeration are always constants.
Because the AccountCategory enumeration was declared as Public, it will be exposed to any application that uses the class.
Another example of enumeration is given below. This example shows how to allow access to an user depending on their username and password.