繁体中文转换为简体中文的PHP函数_PHP

/***********************************************************************
Written by caocao
caocao@eastday.com
http://caocao.oso.com.cn

With the help of Keyes
Keyes2000@263.net
http://my-wjl.scu.edu.cn/~Keyes
***********************************************************************/
function isbig5($code)
{
if (strlen($code)>=2)
{
$code=strtok($code,"");

if (ord($code[0]) < 161)
{
return (0);
}
else
{
if (((ord($code[1]) >= 64)&&(ord($code[1]) <= 126))||((ord($code[1]) >= 161)&&(ord($code[1]) <= 254)))
{
return (1);
}
else
{
return (0);
}
}
}
else
{
return (0);
}
}

function big5offset($code)
{
if (strlen($code) >= 2)
{
$code=strtok($code,"");
if ((ord($code[1]) >= 64)&&(ord($code[1]) <= 126))
{
return ((ord($code[0]) - 161) * 157 + (ord($code[1]) - 64));
}
if ((ord($code[1]) >= 161)&&(ord($code[1]) <= 254))
{
return ((ord($code[0]) - 161) * 157 + 63 + (ord($code[1]) - 161));
}
}
return (-1);
}

function wordtostring($code)
{
return (chr(hexdec(substr($code,0,2))).chr(hexdec(substr($code,2,2))));
}

function big5togb($code)
{
include "data_big5.php";
$output="";
$length=strlen($code);
$code=strtok($code,"");
$idx=0;
while ($idx < $length)
{
$tmpStr=$code[$idx].$code[$idx+1];

if (isbig5($tmpStr))
{
$offset=big5offset($tmpStr);
if (($offset >= 0)||($offset <= 14757))
{
$output.=wordtostring($big5order[$offset]);
$idx++;
}
else
{
$output.= $code[$idx];
}
}
else
{
$output.= $code[$idx];
}
$idx++;
}
return ($output);
}
?>