Guide to PHP and MySQL (University at Buffalo Version)

Chapter 6: Working With Functions

PHP Functions

PHP functions provide a way to create a group of statements that perform a certain task and then "call" that function from PHP code.

<?php
function generate_footer() {
echo ("<footer>\n<p>Copyright © " . date ("Y") . " Jim Gerland</p>\n</footer>\n");
}
generate_footer();
?>

Figure 6-1: A PHP Function

Figure 6-2: A PHP Function Output

The PHP `include` Statement

PHP allows you to have a function in a separate file, such as functions.php and, using the PHP include or include_once statement access that function in any PHP program.

<?php include("generateFooter.php"); ?>
<!doctype html>
<html>
  <head>
    <title>The name of this page</title>
  <head>
  <body>
    <h2>Hello!</h2>
    <p><?php echo("Hello World!"); ?></p>
    <?php generateFooter(); ?>
  </body>
</html>

Figure 6-3: Using include

The rendered web page would look like this:

Hello!

Hello World!

Figure 6-4: PHP include Output

Function Parameters

PHP allows you to pass arguments to a function by declaring them as the parameters of the function.

<?php
function calcSalesTax($price, $tax) {
$total = $price + ($price * $tax);
printf("<p>Total cost: $%.2f</p>\n", $total");
}

calcSalesTax(42.00, 0.0875);
?>

Figure 6-5: Passing Arguments to a Function

Total cost: $45.67

Figure 6-6: Passing Arguments to a Function Output

Using Default Function Parameters

PHP also allows you to have default values parameters if that parameter is not in the arguments passed to a function by assigning a default value to them as the parameters of the function.

<?php
function calcSalesTax2($price, $tax = .0875) {
$total = $price + ($price * $tax);
printf("<p>Total cost: $%.2f</p>\n", $total");
}

calcSalesTax2(42.00);
?>

Figure 6-7: Using Default Arguments with a Function

Total cost: $45.67

Figure 6-8: Using Default Arguments with a Function Output

Using Optional Function Parameters

PHP also allows you to have optional parameters if that parameter is not in the arguments passed to a function.

<?php
function calcSalesTax3($price, $tax = "") {
$total = $price + ($price * $tax);
printf("<p>Total cost: $%.2f</p>\n", $total");
}

calcSalesTax3(42.00);
?>

Figure 6-9: Using Optional Arguments with a Function

Total cost: $42.00

Figure 6-10: Using Optional Arguments with a Function Output

Task - Create a PHP Loop/Array/Function Page

For this task you will copy your index.php file to a new file called lfa.php. You will also create a file called that will hold your PHP functions. You will need to include your functions.php in the code for your index.php file.

Change your JavaScript array function to use a PHP function to display the list (with links) of assignments for this course. The function should manipulate a PHP array.
Use appropriate PHP comments throughout your code.
Use PHP to replace your paragraph about yourself with:
- A function that generates an HTML5/CSS table of three (3) columns: the month number, name of the month, and number of days in that month.
  - This function should use PHP Arrays to the store name of the months and days in each month.
  - This function should use a PHP Loop to walk through the months names array and generate HTML5/CSS to display the table.
  - This function should use a PHP conditional (if) test to determine whether the row is odd or even and use appropriate CSS to make the even rows a different background/foreground color than the odd rows. Hint: use the PHP mod (%) operator in your if statement.
Modify your JavaScript code in your index.html file that uses an array of the Assignments for this course to display an ordered list of these assignments to convert the entry for this assignment to a web link that allows me to download and save your index.php, lfa.php, vars.php, and functions.php files so I can download, save, and grade your work.

You will modify the PHP array function for this item in your index.php page to add a link for this assignment that allows me to view your work.

You *MUST* use the W3C Unicorn Validator to validate your HTML5/CSS3 code.

Then upload your files (images, CSS, js, php, etc.) to your localhost Web Space and add <a> (anchor) tags that utilize the 'download.php' for all the files for this assignment that allow me to download your files to my web server.

Let's Get Started with a PHP function Page!
Let's Get Started with a PHP include Page!