php中文字符怎么转十六进制

<?php
//汉字转换为16进制编码
function hexencode($s) {
    return preg_replace('/(.)/es',"str_pad(dechex(ord('\1')),2,'0',str_pad_left)",$s);    
}
//16进制编码转换为汉字
function hexdecode($s) {
    return preg_replace('/(w{2})/e',"chr(hexdec('\1'))",$s);
}
echo hexdecode(hexencode("北京欢迎您！"));
?>

echo rawurlencode("北京欢迎您").'<br>';

<?php
$string = "北京欢迎您！"; 
$length = strlen($string); 
echo $string; 
$result = array(); 
//十进制 
for($i=0;$i<$length;$i++){ 
if(ord($string[$i])>127){ 
$result[] = ord($string[$i]).' '.ord($string[++$i]); 
} 
} 
var_dump($result); 
echo '<br>';
//十六进制 
$strings = array(); 
foreach($result as $v){ 
$dec = explode(" ",$v); 
$strings[] = dechex($dec[0])." ".dechex($dec[1]); 
} 
var_dump($strings);
utf-8版：
$string = "北京欢迎您！"; 
$length = strlen($string); 
echo $string; 
$result = array(); 
//十进制 
for($i=0;$i<$length;$i++){ 
if(ord($string[$i])>127){ 
$result[] = ord($string[$i]).' '.ord($string[++$i]).' '.ord($string[++$i]); 
} 
} 
var_dump($result); 
echo '<br>';
//十六进制 
$strings = array(); 
foreach($result as $v){ 
$dec = explode(" ",$v); 
$strings[] = dechex($dec[0])." ".dechex($dec[1])." ".dechex($dec[2]); 
} 
var_dump($strings);