Email+URL的判断和自动转换函数

<?php
function validateemail($email)  
{     return eregi("^[_a-z0-9-]+(\.[_a-z0-9-]+)*@[a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,3})$", $email);  
}  

function validateurl($url)  
{     return eregi("^((ht|f)tp://)((([a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,3}))|(([0-9]{1,3}\.){3}([0-9]{1,3})))((/|\?)[a-z0-9~#%&'_\+=:\?\.-]*)*)$", $url);  
}  

function converturls($text)  
{     $text = eregi_replace("((ht|f)tp://www\.|www\.)([a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,3})((/|\?)[a-z0-9~#%&\\/'_\+=:\?\.-]*)*)", "http://www.\\3", $text);  
    $text = eregi_replace("((ht|f)tp://)((([a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,3}))|(([0-9]{1,3}\.){3}([0-9]{1,3})))((/|\?)[a-z0-9~#%&'_\+=:\?\.-]*)*)", "<a href=\"\\0\">\\0</a>", $text);  
    return $text;  
}  

function convertmail($text)  
{     $text = eregi_replace("([_a-z0-9-]+(\.[_a-z0-9-]+)*@[a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,3}))", "<a href='mailto:\\0'>\\0</a>", $text);  
    return $text;  
}  

function convertalllinks($text)  
{     $text = converturls($text);  
    $text = convertmail($text);  
    return $text;  
}
?>