php 将网址字符串转换成超级链接

    function makeClickableLinks($text) {
     $text = eregi_replace('(((f|ht){1}tp://)[-a-zA-Z0-9@:%_+.~#?&//=]+)',
     '<a href="\1">\1</a>', $text);
     $text = eregi_replace('([[:space:]()[{}])(www.[-a-zA-Z0-9@:%_+.~#?&//=]+)',
     '\1<a href="http://\2">\2</a>', $text);
     $text = eregi_replace('([_.0-9a-z-]+@([0-9a-z][0-9a-z-]+.)+[a-z]{2,3})',
     '<a href="mailto:\1">\1</a>', $text);       
    return $text;
    }