mb_convert_encoding( $str, $encoding1,$encoding2 )；

$str，要转换编码的字符串

$encoding1，目标编码，如utf-8,gbk，大小写均可

$encoding2，原编码，如utf-8,gbk，大小写均可

实例1

<?php

$str='编码';

echo mb_convert_encoding($str, "UTF-8"); //编码转换为utf-8

?>

实例2

<?php

$str='编码';

echo mb_convert_encoding($str, "UTF-8", "GBK"); //已知原编码为GBK，转换为utf-8

?>

实例3

<?php

$str='编码';

echo mb_convert_encoding($str, "UTF-8", "auto"); //未知原编码，通过auto自动检测后，转换编码为utf-8

?>