VBScript Procedures

In Modern programming procedures are very useful. Dividing our script into procedures helps us to write and maintain programs by segregating related code into smaller, manageable sections. It also helps to reduce the number of lines of code by reuse the same subroutine or function many times in different situations and from different parts of the program.

Sub Procedure:

is a sequence of statements, enclosed by the Sub and End Sub statements
perform an actions, but does not return a value
can take arguments that are passed to it by a calling procedure
without arguments, must include an empty set of parentheses ()

For creating the sub procedure, start the section of code with the Sub keyword followed by a name for the sub procedure. It must be followed by an opening and closing parentheses so that it differentiate the name of the sub procedure with any other regular name. Always close the section of the sub procedure with End Sub keyword

Sub DisplayFullName()
Dim FirstName, LastName
Dim FullName

FullName = FirstName & " " & LastName
End Sub

Calling a Procedure

You can call procedure from another procedure, function, or control's event in the body section of an HTML file. To call a simple procedure such as the earlier DisplayFullName, you can just write the name of the sub procedure.

Following example shows the above DisplayFullName sub procedure is called when the user clicks the Detail section of the form:

Sub Detailer()
DisplayFullName
End Sub

Passing an Argument

Sometimes a procedure needs one or more values to work on for carrying an assignment then procedure needs a variable called argument. Another procedure might need more that one argument. The number and types of arguments of a procedure depends on different factors.

If you are writing your own procedure, on the basis of your requirement place arguments You also decide on the type of the argument(s). For a procedure that is taking one argument, in the parentheses of the procedure, write a name for the argument. Below is an example:

Sub CalculateArea(Radius)
Dim dblPI
Dim dblArea
dblPI = 3.14159
dblArea = Radius * Radius * dblPI
End Sub

To Call an Argumentative Procedure

There are various ways you call a sub procedure. As we saw already, if a sub procedure doesn't take an argument, you just write its name. If a sub procedure is taking an argument, type the name of the sub procedure followed by the name of the argument. If the sub procedure is taking more than one argument, type the name of the procedure followed by the name of the argument, in the exact order they are passed to the sub procedure, separated by a comma. Below is an example:

Sub Result()
Dim dblHours, dblSalary

CalcAndShowSalary dblHours, dblSalary
End Sub
Sub CalcAndShowSalary(Hours, Salary)
Dim dblResult

dblResult = Hours * Salary
txtResult = dblResult
End Sub

One alternative,to call a sub procedure use the keyword Call.Now in this case, when calling a procedure using Call, you must include the argument(s) between the parentheses. using Call, the above procedure could call the CalcAndShowSalary as follows:

Sub Result()
Dim dblHours As Double
Dim dblSalary As Double

dblHours = txtHours
dblSalary = txtSalary

Call CalcAndShowSalary(dblHours, dblSalary)
End Sub