PHP

Quantifiers

The quantifiers are metacharacters that allow you to dictate how many times something can or must appear. They are greedy, i.e. they match as much as they can.

Character	Meaning
?	0 or 1
*	0 or more
+	1 or more
{x}	Exactly x occurences
{x, y}	Between x and y (inclusive)
{x,}	At least x occurences

<html>
<head>
<title>PHP</title>
<meta Name="Author" Content="Hann So">
</head>
<body>
<p>
<?php
if (isset($_POST['submit'])) {
		process_form();
	}
	else {
		display_form();// display form for the first time
	}

function display_form() {
	echo <<<HTML
	<form action = "$_SERVER[SCRIPT_NAME]" method="post">
	Regular Expression Pattern (include the delimiter):<br />
	<input type="text" name="pattern" value="/w.+d/" /><br />
	Text:<br />
	<input type="text" name="text" size="70"
	value="Welcome to the world of PHP. The Internet world is full of challenges." /><br />
	<input type="submit" name="submit" value="Check" />
	</form>
	<table border>
	<tr bgcolor="lightcyan">
	<th align="left">Regular Expression</th>
	<th align="left">Text</th>
	</tr>
	<tr>
	<td>/c.+t/
	<br />(contains the letters c and t, with one or more letetrs in between)
	</td>
	<td>cool, I like carrots.
	</td>
	</tr>
	<tr bgcolor="lightyellow">
	<td>/^carrots?$/
	<br />(for exact match, use ^ and $.)
	</td>
	<td>cool, I eat a carrot a day. I like carrots.
	</td>
	</tr>
	</table>
HTML;
}

function process_form() {
	// trim the strings
	$pattern = trim($_POST['pattern']);
	$text = trim($_POST['text']);
	echo "The result of checking <br /><font color=red>$pattern</font><br />
	against<br /><font color=red>$text</font><br /> is:<br />";
	// match the pattern
	if (preg_match($pattern, $text, $matches)) {
		echo "$pattern was matched. <br />";
	}
	else {
		echo "$pattern was not matched. <br />";
	}
	echo "<br />The matches array contains:<br />";
	foreach ($matches as $key =>$values) {
		echo $key, " => ", $values, "<br />";
	}
	echo "<br /><a href=\"$_SERVER[SCRIPT_NAME]\">Check again?</a>";

}
?>
</p>
</body>
</html>

View the effect