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) ...Get Web Database Applications with PHP, and MySQL now with the O’Reilly learning platform.
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