Variables of different data types when combined as a single variable to hold
several related informations is called a User-Defined data type.
A Type statement is used to define a user-defined type in the General declaration
section of a form or module. User-defined data types can only be private in form
while in standard modules can be public or private. An example for a user defined
data type to hold the product details is as given below.
Private Type ProductDetails
ProdID as String
ProdName as String
Price as Currency
End Type
The user defined data type can be declared with a variable using the Dim statement
as in any other variable declaration statement. An array of these user-defined
data types can also be declared. An example to consolidate these two features
is given below.
Dim ElectronicGoods as ProductDetails ' One Record
Dim ElectronicGoods(10) as ProductDetails ' An array of 11 records
A User-Defined data type can be referenced in an application by using the variable
name in the procedure along with the item name in the Type block. Say, for example
if the text property of a TextBox namely text1 is to be assigned the name of the
electronic good, the statement can be written as given below.
Text1.Text = ElectronicGoods.ProdName
If the same is implemented as an array, then the statement becomes
Text1.Text = ElectronicGoods(i).ProdName
User-defined data types can also be passed to procedures to allow many related
items as one argument.
Sub ProdData( ElectronicGoods as ProductDetails)
Text1.Text = ElectronicGoods.ProdName
Text1.Text = ElectronicGoods.Price
End Sub
