Functions in ASP.NET

Functions

Variables

Variables are used to store data. A variable has a name to which we refer and the data type, the type of data the variable holds. You need to declare variables before using them. Variables are declared with the Dim keyword and Dim stands for Dimension.

Variables Sample

The following code creates two variables, adds them and stores the sum in a third variable.

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As_
System.EventArgs) Handles MyBase.Load
Dim x As Integer = 10
Dim y As Integer = 20
Dim z As Integer = x + y
Response.Write("Sum is" & " " & z)
End Sub

Constants

When we have certain values that we frequently use while programming, we should use Constants. A value declared as constant is of fixed value that cannot be changed once set. Constants should be declared as Public if we want it to be accessed by all parts of the application. We use the Const keyword to declare a constant. The following line of code declares a constant:
Public Const Pi as Double=3.14159265

SubProcedures

Procedures are a series of statements that are executed when called. Procedures makes us handle the code in a simple and organized fashion. Sub procedures are procedures which do not return a value. Each time when the Sub procedure is called, the statements within it are executed until the matching End Sub is encountered. The Page_Load event, which is the starting point of the program itself is a sub procedure. When the application starts execution, the control is transferred to Page_Load procedure automatically which is called by default.

SubProcedures Sample

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As_
System.EventArgs) Handles MyBase.Load
Display()
'control looks for a sub procedure named Display() and executes it
End Sub

Sub Display()
Response.Write("In Sub Procedure")
End Sub

Functions

Function is a Procedure which returns a value. Functions are used to evaluate data, make calculations, or to transform data. Declaring a Function is similar to declaring a Sub procedure but functions are declared with the Function keyword. The following is an example on Functions. This simple application is an online loan repayment calculator that asks the user to enter the amount he wants to borrow, the duration of the loan and based on that information calculates his monthly repayments. To start, drag four labels, two textboxes and a button from the toolbox on to the Web Forms page. Open the code designer and paste the following code. Look at Live Code demo towards the botom of this page for user interface design.

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As_
System.EventArgs) Handles Button1.Click
Calc()
'when the user submits his data, control passes to Calc function
End Sub

Public Function Calc() As Long
Dim amt, temp, temp1, totinterest, mi, mitemp, tot As Double
'declaring the required variables
temp = CInt(TextBox1.Text) * 13
'multiplying the amount the user wants to borrow with 13.Assuming the
'interest rate to be 13%
totinterest = temp / 100
'calculating the interest amount for the amount entered
mitemp = CInt(TextBox2.Text) * 12
'multipling the years entered with 12 to get the number of months
mi = totinterest / mitemp
'calculating monthly interest
temp1 = CInt(TextBox2.Text) * 12
'multipling the years entered with 12 to get the number of months
amt = CInt(TextBox1.Text) / temp1
'dividing the amount borrowed with number of months it is borrowed for
tot = amt + mi
'calculating the total by adding the amount + monthly interest
Label1.Text = "Your monthly repayment is:" & " " & Int(tot)
disp()
End Function

Public Sub Disp()
Label4.Text = "Not Satisfied? Would you like to try another option?"
End Sub

Live Code Demo

Functions

XYZ Loan Repayment Calculator

Enter the amount you wish to borrow

Enter your loan repayment period in years