/**
* This method is to check if a string contains Simplified Chinese (GB2312).
* 
* @param $string 
* @return boolean returns true, if it has GB2312 chars.
* 
*/
function hasChnGBWord($string){

    if (!($len=strlen($string))) return false;
    
    for($i=0;$i<$len;$i++) {
        if (isChnGBWord($string[$i],$string[$i+1])) return true;	
    }
	
    return false;
}


/**
* This method is to check if a word is a Simplified Chinese (GB2312).
* 
* Each GB2312 character contains two bytes, the higher byte and the lower byte.  
* 
* @param $higherByte 
* @param $lowerByte 
* @return boolean returns true, if it is a GB2312 word
* 
*/
function isChnGBWord($higherByte,$lowerByte){
    $higher=char2u_int($higherByte);
    $lower=char2u_int($lowerByte);
	
    $val=($higher & 0x80)?(($lower & 0x80)?1:-1):0;  //If -1==$val, then error occurs!  It is a half Chinese character.
	
    return (1==$val);
}

/**
* This method is to convert a character into unsigned int.
*   
* @param $char the input character
* @return int 0 if error occurs
* 
*/
function char2u_int($char){
    $str=bin2hex($char);

    $val=0;
    for($i=0;$i<2;$i++){
        $c=ord($str[$i]);
        
        if ($c>=48 && $c<=57) $c-=48;      //between '0' and '9'
        elseif($c>=65 && $c<=70) $c-=55;   //between 'A' and 'F'
        elseif($c>=97 && $c<=102) $c-=87;  //between 'a' and 'f'
        else $c=0;                         //error! use ascii char as default
		
        if (0==$i) $c*=16;   //high bit
		
        $val+=$c;
    }
	
    return $val;
}