PHP Unicode編碼相互轉換

<?php
/**
* $str 原始中文字符串
* $encoding 原始字符串的編碼，默認utf-8
* $prefix 編碼后的前綴，默認"&#"
* $postfix 編碼后的后綴，默認";"
*/
function unicode_encode($str, $encoding = 'utf-8', $prefix = '&#', $postfix = ';') {
    //將字符串拆分
    $str = iconv("UTF-8", "gb2312", $str);
    $cind = 0;
    $arr_cont = array();

    for ($i = 0; $i < strlen($str); $i++) {
        if (strlen(substr($str, $cind, 1)) > 0) {
            if (ord(substr($str, $cind, 1)) < 0xA1) { //如果為英文則取1個字節 
                array_push($arr_cont, substr($str, $cind, 1));
                $cind++;
            } else {
                array_push($arr_cont, substr($str, $cind, 2));
                $cind+=2;
            }
        }
    }
    foreach ($arr_cont as &$row) {
        $row = iconv("gb2312", "UTF-8", $row);
    }

    //轉換Unicode碼
    foreach ($arr_cont as $key => $value) {
        $unicodestr.= $prefix . base_convert(bin2hex(iconv('utf-8', 'UCS-4', $value)), 16, 10) .$postfix;
    }

    return $unicodestr;
}

/**
* $str Unicode編碼后的字符串
* $decoding 原始字符串的編碼，默認utf-8
* $prefix 編碼字符串的前綴，默認"&#"
* $postfix 編碼字符串的后綴，默認";"
*/
function unicode_decode($unistr, $encoding = 'utf-8', $prefix = '&#', $postfix = ';') {
    $arruni = explode($prefix, $unistr);
    $unistr = '';
    for ($i = 1, $len = count($arruni); $i < $len; $i++) {
        if (strlen($postfix) > 0) {
            $arruni[$i] = substr($arruni[$i], 0, strlen($arruni[$i]) - strlen($postfix));
        }
        $temp = intval($arruni[$i]);
        $unistr .= ($temp < 256) ? chr(0) . chr($temp) : chr($temp / 256) . chr($temp % 256);
    }
    return iconv('UCS-2', $encoding, $unistr);
}

$str = "PHP二次開發：www.php2.cc";

$unistr = unicode_encode($str);
$unistr2 = unicode_decode($unistr);
echo $unistr . '<br />';
echo $unistr2 . '<br />';

$unistr = unicode_encode($str,'GBK','\\u');
$unistr2 = unicode_decode($unistr,'GBK','\\u');
echo $unistr . '<br />';
echo $unistr2 . '<br />';