php正则表达式替换URL链接地址为指定url

$str = "The quick brown fox jumped over the lazy dog.";
$str = preg_replace('/s/','-',$str);
echo $str;
?>
输出结果为：

The-quick-brown-fox-jumped-over-the-lazy-dog.

$str = "The quick brown fox jumped over the lazy dog.";

$patterns[0] = "/quick/";
$patterns[1] = "/brown/";
$patterns[2] = "/fox/";

$replacements[2] = "bear";
$replacements[1] = "black";
$replacements[0] = "slow";

print preg_replace($patterns, $replacements, $str);
/*输出：
The bear black slow jumped over the lazy dog.
*/
ksort($replacements);
print preg_replace($patterns, $replacements, $str);
/*输出：
The slow black bear jumped over the lazy dog.
*/
?>

$a = 'Bootstrap中文网提供Bootstrap中文手册，学习Bootstrap入门教程，Bootstrap是Twitter推出的一个用于前端开发的开源工具包。它由Twitter的设计师Mark Otto和Jacob Thornton合作开发，是一个CSS/HTML框架。Bootstrap中文网致力于为广大国内开发者提供详尽的中文文档、代码实例等，助力开发者掌握并使用这一框架。';

$lines_string=preg_replace("(]*>(.+?))","$1",$a);
print_r($lines_string);
?>