<?php
mb_convert_encoding() 该函数会根据内容自动识别编码,但是执行效率比iconv差；
$content = mb_convert_encoding($content, "utf-8", "gb2312");
$content = iconv("utf-8", "gb2312//IGNORE", $content); //utf-8转gbk
$content = iconv("gb2312", "utf-8//IGNORE", $content); //gb2312换为utf-8
?>