|
Home::Web Development
Functions and Subroutines in ASP
Author : Rob Collyer
Functions and Subroutines in ASP
If you read our http://www.webforumz.com/portal.asp?ContentID=12&CategoryID=2">Tutorial on Include Files (SSI) then you learned how to encapsulate ASP code within include files and the benefits it brings us.
As developers, we should endeavour to make our lives easier wherever possible... no one wants to re-invent the wheel after all.
Functions and Subroutines exist to not only save us time, but to bring power to our ASP.
They are just another way of encapsulating code, but have a lot more functionality than just 'saving some code for later'.
First, let's look at Functions... Imagine a balloon salesman in the street. We've all seen them they require one piece of information when you buy a balloon, the colour.
Let say we asked for a red balloon... The balloon salesman armed with this 'information' then does a pretty basic action... he hands you the balloon. The balloon you received is a direct result of the information you gave the balloon seller.
Functions are just the same... they return to you a value based on the information you provided. Lets look at an example Function: -
<%
Function getBalloon(strColour)
Dim Tempstr
strColour = lcase(strColour) 'This converts the value lowercase.
Select Case strColour
Case "red" Tempstr = "Here is your red balloon"
Case "yellow" Tempstr = "Here is your yellow balloon"
Case "green" Tempstr = "Here is your green balloon"
Case "blue" Tempstr = "Here is your blue balloon"
Case Else Tempstr = "Sorry, we have sold out of that Colour"
End Select
getBalloon = Tempstr
End Function
%>
A Function is passed some information. The information we pass a Function, is known as an 'argument'. The information we get back from a Function is known as the 'return value'. Whilst a Function can have many arguments, it can only have one return value.
Let us look at one more example: -
<%
Function calcTax(amount, taxrate)
Dim Tempvar
Tempvar = amount * (taxrate / 100)
CalcTax = Round(Tempvar, 2) 'round the result to 2 decimal places
End Function
%>
Again, another basic example. We should notice this time that the Function accepts two arguments.
By now, we have some idea of how to write a Function. How do we use one?
Let me show you now how we can use the calcTax example.
<%
shoppingbill=goodsTotal + calcTax(goodsTotal,17.5)
Response.Write "Your shopping came to £" & goodsTotal
Response.Write "
VAT amount = £" & calcTax(goodsTotal)
Response.Write "Total Amount Due = £" & shoppingbill
%>
Above you see the example function in action... easy huh!
I have tried to make understanding Functions as easy as possible... Understanding a Subroutine (Sub) is now going to be easy for you. Imagine a block of code that performed some instructions based on information you gave it...
Sounds very much like a function, doesn?t it? Well this time, we do not get anything back. A sub does NOT pass back information it just uses the data we give it for some purpose.
I will use only one example of a Sub, and in the same example make use of the sub: -
<%
Sub Bday(strName, intAge)
Response.Write "Happy Birthday " & Name
Response.Write ", You are " & intAge & " years old today"
End Sub
'now, call the sub
bDay "Joe",26
%>
The above Sub, demonstrates my point. We put something in, it performs an action (in this case writing to the screen), but nothing is returned to us in the code. One thing that REALLY IS important when using a sub, is that we do not put brackets around the arguments... Because we do not have a return value we do not need brackets and in this case, if we try we will get an error.
Well, that just about concludes this article. We should by now be writing efficient code with the use of Functions and Subs. Don?t forget that if you use your functions and subs in multiple pages then you should really store them within include files for reasons of easy maintenance and better performance.
Rob Collyer, experienced with 20 years programming knowledge and site administrator of http://www.webforumz.com">www.webforumz.com - Copyright 2003-2004 Spam emails More free articles Related articles
|
More related feeds |
functions and subroutines in asp
functions and subroutines in asp if you read our tutorial on include files (ssi) then you learned how to encapsulate asp code within include files and the benefits it brings us. as developers, we should endeavour to make our lives ...active server pages 3 0 your visual blueprint for developing ...
this is an indispensable and valuable guide for novice asp programmers. –stephen w. plain. topics covered:. personal web server (pws); vbscript; variables; statement syntax; control structures; functions and subroutines; cookies ... .net documentation tool 9.3 (c#/vb.net)
net functions and subroutines. improved the syntax highlighting of vb.net and c# application source code. the documentation has been revised. the gui now shows a warning that the component folder path is not always required as the ... (ARTICLE) Exception Handling Techniques in ASP.NET | C4Swimmers ...
Error sub as such: (Visual Studio will complete the code if you click either the Overrides or BaseClass events in the editor). The two functions you can use (one or the other, both will not work as only one will get called) ... Is it possible to pass a subroutine to another subroutine? - Perl
I realize that using the END block I can run these subroutines, however I have hundreds of these test to write and there is various formatting, etc, that is repetitious... so I want to include a single function in my END block that will ... Visual Basic - Function Works... | DreamInCode.net
End Function. VB functions are not subroutines, you do not call them. Also isSquare expects an integer. You need to convert the text string to an integer. vb. If isSquare(Val(txtvalue.Text)) Then ... ASP shopping cart
This page is simply a collection of functions and subroutines that make database calls or display HTML messages. These functions and subroutines are all called from the basket.asp page. It is generally good design to break out sections ... Success on the Web: Migrating from Classic ASP to ASP.Net
Each submit button is also a user control, like other form fields, and each button has a parameter that indicates with subroutine the button submits to. In Classic ASP all the functions and subroutines are enclosed in the standard ... VB.NET - Soapmapper Error Using MS Access + SOAP + Web Service ...
'This subroutine is the class error handler. It can be called from any class subroutine or function 'when that subroutine or function encounters an error. Then, it will raise the error along with the 'name of the calling subroutine or ... (TUTORIAL) C++ Programming | C4Swimmers.Net - India's Largest ...
I have heard people say things like ``As a performance optimization, I've removed all virtual functions and replaced the virtual function calls with switch statements and ordinary member function calls.'' That is a major performance ...
|
|
|
