Modulus Usage

[AikenDrum]

Hi there,

 

I am looking for help with the following :

 

I have cameras.

I have dvr's - 3 types - 4 channel, 8 channel, and 16 channel.

Someone on the web page enters the amount of cameras -

I need to work out how many dvr's (dependent on  channels) they need

 

My code so far is pretty poor -

 

if($qty % 4 >= 0){
$dvr = 4;
}
if ($qty > 4 && $qty < 9) 
{  
$dvr = 8;
}
if ($qty > 8 && $qty < 17) 
{  
$dvr = 16;
}
if ($qty > 16) 
{  
$mod = $qty % 4;
echo "mod = ". $mod."<br><br>";
}

echo "You need a ".$dvr. " port dvr";

 

Example - if $qty=19;

It should read  "1 * 16 port dvr and 1 * 4 port dvr"

 

Example - if $qty=24;

It should read  "1 * 16 port dvr and 1 * 8 port dvr"

 

Example - if $qty=30;

It should read  "2 * 16 port dvr"

 

I tried mucking around with the mod function - and probably need some sort of recursion - but am a bit lost now.

 

Any help greatly appreciated

 

kindest Regards

 

AIken D

[kathas]

Correct me if I understood wrong.

 

you need to cover all the cameras with the minimum amount of dvrs ???

 

if so a loop will do

// $qty your variable
$dvrs = array(16=>0,8=>0,4=>0);

while ($qty > 0)
{

if ($qty > 
{
$dvr[16]++;
$qty-=16;
}
else if ($qty > 4)
{
$dvr[8]++;
$qty-=8;
}
else
{
$dvr[4]++;
$qty-=4;
}

}

 

 

[AikenDrum]

Hey Kathas -

 

that's it !

 

MANY thanks - works a treat

 

Kindest Regards

 

AikenD

[AikenDrum]

Hi there -

 

sorry - I spoke to soon. I have found what I think is a bug:

 

Example 1:

Qty = 24

Array ( [16] => 1 [8] => 1 )

CORRECT

 

Example 2:

Qty = 25

Array ( [16] => 2 )

WRONG

 

I would expect to see 

( [16] => 1 [8] => 1 [4] =>1 )

 

Excuse me if I was not clear enough -

 

Minimum ports for 25 cameras = 1*16 + 1*8 + 1*4

 

Perhaps you can see whay is wrong ?

 

Thank you very much

 

AikenD

[yozyk]

$dvr16 = floor($qty/16);
$dvr8  = floor(($qty-16*$dvr16)/8);
$dvr4  = ceil(($qty-16*$dvr16-8*$dvr8)/4);