A structure is a generalization of the user-defined type. In addition to fields, it can expose properties, methods, and events. A structure can implement one or more interfaces, and you can declare individual access levels for each field.
You can declare a structure using the Structure statement. You can specify the access level of a structure using the Public, Protected, Friend, or Private keyword.
Let's consider the following simple example where we have declared a structure named Point3D, which contains three integers X, Y, and Z.
Public Structure Point3D
Public X As Integer
Public Y As Integer
Public Z As Integer
End Structure
Structures are also used to represent a record. For example, if you want to keep track of all your customers, you can add the following fields to the structure.
Public Structure CustomerInfo
Public Id As Integer
Public Name As String
Public Address As String
End Structure
To use the structure, you can create its object using with or without the new keyword.
Public Sub Example1()
Dim point1 As Point3D
Dim point2 As Point3D = New Point3D()
point1.X = 10
point1.Y = 20
point1.Z = 30
point2.X = 40
point2.Y = 50
point2.Z = 60
Console.WriteLine("X: {0}, Y: {1}, Z: {2}", point1.X, point1.Y, point1.Z)
Console.WriteLine("X: {0}, Y: {1}, Z: {2}", point2.X, point2.Y, point2.Z)
End Sub
Let's run the above code and it will print the following output on the console window.
X: 10, Y: 20, Z: 30
X: 40, Y: 50, Z: 60
A Structure only supports constructors that contain parameters. Here in the CustomerInfo structure, a parametrized constructor is added.
Public Structure CustomerInfo
Public Id As Integer
Public Name As String
Public Address As String
Public Sub New(ByVal id As Integer, ByVal name As String, ByVal address As String)
Me.Id = id
Me.Name = name
Me.Address = address
End Sub
End Structure
You can create its object by calling the parameterized constructor.
Public Sub Example2()
Dim customer As CustomerInfo = New CustomerInfo(1, "Mark", "22 wall street")
Console.WriteLine("Id: {0}, Name: {1}, Address: {2}", customer.Id, customer.Name, customer.Address)
End Sub
Let's run the above code, and it will print the following output on the console window.
Id: 1, Name: Mark, Address: 22 wall street
You can also add methods to your structure in C#. Here is a simple method Print() which will print all the information of a customer on the console window.
Public Structure CustomerInfo
Public Id As Integer
Public Name As String
Public Address As String
Public Sub New(ByVal id As Integer, ByVal name As String, ByVal address As String)
Me.Id = id
Me.Name = name
Me.Address = address
End Sub
Public Sub Print()
Console.WriteLine("Id: {0}, Name: {1}, Address: {2}", Me.Id, Me.Name, Me.Address)
End Sub
End Structure
Now to print the customer information, we just need to call the Print() method.
Public Sub Example3()
Dim customer As CustomerInfo = New CustomerInfo(1, "Mark", "22 wall street")
customer.Print()
End Sub
Let's run the above code and it will print the following output on the console window.
Id: 2, Name: John, Address: 11 wall street
When you are working with structures, you must keep in mind the following limitations.