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 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: -
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: -
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.
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: -
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 tutorial on include files (ssi) - Copyright 2003-2004
cleaning team near Winnetka ..Getting a Targeted Visitor to a website is a waste... Read More
Before you jump into spending coutnless hours on designing and... Read More
You have permission to publish this article electronically, in print,... Read More
Your ObjectiveYour small business needs an appealing and professional website... Read More
Simply ensuring your website is accessible to screen reader users... Read More
When you purchase a new item from a Yahoo! Store,... Read More
Starting a business online is no longer as difficult as... Read More
Why do some web sites reap huge benefits while others... Read More
So your prospect, Mary, is sitting at the computer reading... Read More
The evolution of web development parallels the model of technology... Read More
When visitors add your web site to their Favorites or... Read More
Do you need a web site? Are you considering getting... Read More
Dynamically Update Your Web Pages Via E-MailIf you can Send... Read More
You work hard to build traffic to your web page.... Read More
Most people know they need a website in order to... Read More
Like most average persons, I wanted some extra money to... Read More
Website, website, website, everyone says you need one. But do... Read More
A website is lifeline of internet home business. In order... Read More
The art of turning website visitors into paying customers depends... Read More
One of the biggest mistakes that most online retailers make... Read More
"What's in it for me?" you ask. "Why should I... Read More
"How do I improve web site sales figures?" The CEO... Read More
Your site is fast and getting traffic, but conversion rates... Read More
Does My Web Site Require A Web Database?If your web... Read More
If you were asked to put a value on your... Read More
family-safe home cleaners Northbrook ..If you were asked to put a value on your... Read More
Thousands of people are now making a living online and... Read More
Creating and maintaining an effective presence on the Web has... Read More
Web sites are not just places to sell things; they... Read More
Like wine cars get more attractive to collectors as years... Read More
Recently, a friend asked "What's the deal with those DIY... Read More
Starting an internet business can be confusing to non-veterans. The... Read More
"'Page Not Found' on this Server. Check the URL and... Read More
SummaryHere's the scoop on what you must know when designing... Read More
The first step in setting up an online business...Starting an... Read More
Visitors to your site come looking for information or solutions... Read More
There are millions and millions of websites on the Internet.... Read More
What to put your the website if you are an... Read More
It's now easier than ever to take payments on the... Read More
Are you, like many other website owners, frustrated at the... Read More
You have seen those web pages where they have the... Read More
Right after the thought, "I need a website," people usually... Read More
An accessible Web site is easily approached, easily understood, and... Read More
When people think about the Internet, they think about technology.... Read More
Are you aware that 90% of the websites on the... Read More
Setting up a website is the very first step of... Read More
Some left shoes are in isle 5, while the right... Read More
I am just a learner who likes to delve in... Read More
First, an eye opener. Making your fortune through affiliate programs... Read More
Having an eye catching website is great, but are you... Read More
Web Development |