Question

I am trying to grasp the concept of PHP functions. I know how to create one.

function functionName()
{
    //code to be executed;
}

I also know how to call a function. I am just a little confused as to what a parameter is for. I have read the php manual and w3schools.com’s tutorial. From my understanding, you need a parameter to pass a value to the function? If that is correct why not just create it within the function? Why use a parameter?

Like this:

<?php
function num()
{
$s=14;
echo $s;
}
num();
 ?>  

I know you can do:

<?php
function num($s=14)
{
    echo $s;
}
num();
?>

or:

<?php
function num($s)
{
    echo $s;
}
num($s=14);
?>

Could someone give me a real application of using a parameter, for say maybe a user based dynamic content website? I think it would help me understand it better.

Answer 1

Passing a parameter allows you to use one function numerous times. For example:

If you wanted to write ONE function that sent mail – you could pass the following parameters:

$to = $_POST['to'];
$from = $_POST['from'];
$subject = $_POST['subject'];

Then, in your function:

 function sendmail($to, $from, $subject){

//code to be executed

}

Now you can reuse your send function at various points in your web app.