PHP提取字符串中的图片地址[正则表达式]

代码如下:

<?php 
$str='<p><img border="0" src="upfiles/2009/07/1246430143_1.jpg" /> 结果显示： 
Array 
( 
[0] => Array 
( 
[0] => <img border="0" src="upfiles/2009/07/1246430143_1.jpg" /> ) 

[1] => Array 
( 
[0] => upfiles/2009/07/1246430143_1.jpg 
) 
)