php把字符串转为utf-8的方法：首先找出字符串本身的编码；然后通过“mb_convert_encoding($str, 'UTF-8', $current_encode);”方法把字符串转为utf-8即可。
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php将任意编码的内容转换成utf-8
先找出字符串本身的编码，再转换为utf-8编码。
方法
function str_to_utf8 ($str = '') {
$current_encode = mb_detect_encoding($str, array("ASCII","GB2312","GBK",'BIG5','UTF-8'));
$encoded_str = mb_convert_encoding($str, 'UTF-8', $current_encode);
return $encoded_str;
}