文字编码的转换mb_convert_encoding()
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 
$str='绿夏网:http://www.gimoo.net'; 
echo mb_convert_encoding($str, "UTF-8"); //编码转换为utf-8 
?> 

<?php 
$str='绿夏网:http://www.gimoo.net'; 
echo mb_convert_encoding($str, "UTF-8", "GBK"); //已知原编码为GBK，转换为utf-8 
?> 

<?php 
$str='绿夏网:http://www.gimoo.net'; 
echo mb_convert_encoding($str, "UTF-8", "auto"); //未知原编码，通过auto自动检测后，转换编码为utf-8 
?> 

PHP下编码转换函数mb_convert_encoding与iconv的使用说明

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