March 2002
Intermediate to advanced
592 pages
15h 52m
English
Content preview from Web Database Applications with PHP, and MySQLBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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User-Defined Functions
Functions provide a way to group together related statements into a cohesive block. For reusable code, a function saves duplicating statements and makes maintenance of the code easier.
We’ve already presented many examples of function calls in this chapter. Once written, a user-defined function is called in exactly the same way. Consider an example of a simple user-developed function as shown in Example 2-6.
Example 2-6. A user-defined function to output bold text
<!DOCTYPE HTML PUBLIC
"-//W3C//DTD HTML 4.0 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<title>Simple Function Call</title>
</head>
<body bgcolor="#ffffff">
<?php
function bold($string)
{
echo "<b>" . $string . "</b>\n";
}
// First example function call (with a static string)
echo "this is not bold\n";
bold("this is bold");
echo "this is again not bold\n";
// Second example function call (with a variable)
$myString = "this is bold";
bold($myString);
?>
</body></html>The script defines the function bold( )
, which
takes one parameter, $string, and prints that
string prefixed by a bold <b> tag and
suffixed with a </b> tag. The
bold( ) function, defined here, can be used with
a string literal expression or a variable, as shown.
Functions can also return values. For example, consider the following
code fragment that declares and uses a function heading( )
,
which returns a string using the return statement:
function heading($text, $headingLevel) { switch ($headingLevel) ...Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.