The user defined type in Visual Basic 6 is a compound data structure. It holds several variables of different data types. After defining a UDT, you can assign values to the member variables of the UDT.
Defining the user defined type
Before using the UDT in your code, you must first define it using the Type directive in the Declarations section of a module, for example, a form module. The following block of code is called the Type structure.
Example
Private Type BookDetails 'in Declarations section
title As String
author As String
pages As Long
End Type
After defining the UDT variable, declare variables of that type.
Assigning values
Private Sub cmdSetValue_Click()
Dim book1 As BookDetails 'Declaring book1 as the type BookDetails
'Assigning values
book1.author = "Balagurusamy"
book1.title = "C Programming"
book1.pages = 600
End Sub
With…End with
Use “With…End with” structure for the better readability of your code. It eases up the structure.
Example
Dim book1 As BookDetails
With book1
.author = "Balagurusamy"
.title = "C Programming"
.pages = 600
End With
With book1
Print .author, .pages, .title
End With
Sub structure of a user defined type
The Type structure can also have sub structures. In this case, you have to access the nested structure using the nested “With…End With” structure.
Example
'Sub structure of UDT
Private Type AddressDetails
city As String
state As String
pin As Long
ph_no As String
End Type
Private Type StudentDetails
name As String
stream As String
DepartmentId As String
address As AddressDetails
End Type
Private Sub cmdSetDetails_Click()
Dim student1 As StudentDetails
'Nested With...End With structure
With student1
.name = "XYZ"
.stream = "Computer Science"
.DepartmentId = "C900"
MsgBox .name & vbTab & .stream & vbTab & .DepartmentId
With .address
.city = "London"
.state = "abc gdf"
.pin = 77764
.ph_no = "998765432"
MsgBox .city & vbTab & .ph_no & vbTab & .pin & vbTab _
& .state
End With
End With
End Sub