class DecimalToHEX
{
    public function __construct($decimalRed, $decimalGreen, $decimalBlue)
    {
        $this->decimalRed = $decimalRed;
        $this->decimalGreen = $decimalGreen;
        $this->decimalBlue = $decimalBlue;
    }
    public function getInvertHEXBits($divide)
    {
        $divider = 16;
        $intPart = 0;
        $reminder[0] = 0;
        $remInd = 0;
        while($divide > 0)
        {
            $intPart = intval($divide / $divider);
            $reminder[$remInd] = $divide - ($intPart * $divider);
            $remInd++;
            $divide = $intPart;
        }
        return $reminder;
    }
    public function getHEX($decimal)
    {
        $invertMassOfBits = $this->getInvertHEXBits($decimal);
        $normalMassOfBits = array();
        $numOfBits = count($invertMassOfBits);
        $i = 1;
        $HEXStr = '';
        
        foreach($invertMassOfBits  as $val)
        {
            
            if($val > 9)
            {
                
                switch ($val)
                {
                    
                    case  10 : 
                    $val = 'A';
                    break;
                    
                    case  11 : 
                    $val = 'B';
                    break;
                    
                    case  12 : 
                    $val = 'C';
                    break;
                    
                    case  13 : 
                    $val = 'D';
                    break;
                    
                    case  14 : 
                    $val = 'E';
                    break;
                    
                    case  15 : 
                    $val = 'F';
                    break;
                }
            }
            $normalMassOfBits[$numOfBits - $i] = $val;
            $HEXStr .= $val;
            $i++;
        }
        $normalMassOfBits[$numOfBits + 1] = $HEXStr;
//содержит массив битов + последний бит - всё число HEX 
        return $HEXStr;
    }
    public function GetSummaryHEX()
    {
        
        if(iconv_strlen($this->getHEX($this->decimalRed)) > 1)
        {
            $massHEX[0] = $this->getHEX($this->decimalRed);
        }
        else 
        {
            $massHEX[0] = '0'. $this->getHEX($this->decimalRed);
        }
        
        if(iconv_strlen($this->getHEX($this->decimalGreen)) > 1)
        {
            $massHEX[1] = $this->getHEX($this->decimalGreen);
        }
        else 
        {
            $massHEX[1] = '0'. $this->getHEX($this->decimalGreen);
        }
        
        if(iconv_strlen($this->getHEX($this->decimalBlue)) > 1)
        {
            $massHEX[2] = $this->getHEX($this->decimalBlue);
        }
        else 
        {
            $massHEX[2] = '0'. $this->getHEX($this->decimalBlue);
        }
//$massHEX[0] = $this->getHEX($this->decimalRed); 
//$massHEX[1] = $this->getHEX($this->decimalGreen); 
//$massHEX[2] = $this->getHEX($this->decimalBlue); 
        $sumHEX = $massHEX[0] . $massHEX[1] . $massHEX[2];
        return $sumHEX;
    }
    
}
echo '<form name="color" method="post" action="'. $_SERVER['PHP_SELF'] .'">';
echo '<input type=text size=5 name=red value="">';
echo '<input type=text size=5 name=green value="">';
echo '<input type=text size=5 name=blue value="">';
echo '<input type=submit>';
echo '</form>';
$decimal = new DecimalToHEX($_POST['red'], $_POST['green'], $_POST['blue']);
$pp = $decimal -> GetSummaryHEX();
echo 'HEX: '. $pp;

Спустя 4 минуты, 52 секунды (26.07.2011 - 15:04) svolota написал(а):

Цитата (Invis1ble @ 26.07.2011 - 11:59)

что-то не понятно, чем не подходит штатная dechex() ?

Ну... вот такое вот задание , видимо важна концепция а не ответ в виде 13981010 = 2222216

public function getHEX($decimal)
	    {
		 $invertMassOfBits = $this->getInvertHEXBits($decimal);
		 $normalMassOfBits = array();
		 
		 $numOfBits = count($invertMassOfBits);
		 $i=0;
		 $HEXStr='';
		 foreach ($invertMassOfBits as $val)
		    {
			 if($val>9)
			    {
                 switch($val)
                    {
					 case 10: $val='A'; break;
					 case 11: $val='B'; break;
					 case 12: $val='C'; break;
					 case 13: $val='D'; break;
					 case 14: $val='E'; break;
					 case 15: $val='F'; break;
					}				 
				}
			 $invertMassOfBits[$i]=$val;
			 $i++;
			}
		 $normalMassOfBits=array_reverse($invertMassOfBits);
         foreach($normalMassOfBits as $val)
            {
			 $HEXStr .= $val;
			}		 
		 return $HEXStr;
		}