<分区>
在下面的代码中，我不知道这些字符在功能上有何不同:\r\t\n。有人对此有解释或描述吗？
下面是一些示例代码:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title>Sorting words in a block of text by length</title>
<link rel="stylesheet" type="text/css" href="common.css" />
</head>
<body>
<h1>Sorting words in a block of text by length</h1>
<?php
$myText = <<<END_TEXT
But think not that this famous town has
only harpooneers, cannibals, and
bumpkins to show her visitors. Not at
all. Still New Bedford is a queer place.
Had it not been for us whalemen, that
tract of land would this day perhaps
have been in as howling condition as the
coast of Labrador.
END_TEXT;
echo "<h2>The text:</h2>";
echo "<div style=\"width: 30em;\">$myText</div>";
$myText = preg_replace( "/[\,\.]/", "", $myText );
$words = array_unique( preg_split( "/[ \n\r\t]+/", $myText ) );
usort( $words, create_function( '$a, $b', 'return strlen($a) - strlen($b);
' ) );
echo "<h2>The sorted words:</h2>";
echo "<div style=\"width: 30em;\">";
foreach ( $words as $word ) {
echo "$word ";
}
echo "</div>";
?>
</body>
</html>