Building array keys using a span of numbers for like values

Question

I am calculating discounts based on a quantity after 6.

Is there a cleaner way to do this:

$leg_directory_discount = array(
 6 => .50,
 7 => .50,
 8 => .50,
 9 => .50,
 10 => .50,
 11 => 1,
 12 => 1,
 13 => 1,
 14 => 1,
 15 => 1,
 16 => 1,
 17 => 1,
 18 => 1,
 19 => 1,
 20 => 1,
 21 => 1.5,
 22 => 1.5,
 23 => 1.5,
 24 => 1.5,
 25 => 1.5,
 26 => 1.5,
 27 => 1.5,
 28 => 1.5,
 29 => 1.5,
 30 => 1.5,
 31 => 1.5,
 32 => 1.5,
 33 => 1.5,
 34 => 1.5,
 35 => 1.5,
 36 => 1.5,
 37 => 1.5,
 38 => 1.5,
);

edit: The max and min values of the discounts never change. Here is how I'm calculating the discount and arriving at the final price:

if($v[0]['leg_discount'] == '1' && $v[0]['qty'] >= 6){
 $discount = $qty * $leg_directory_discount[$qty];
 $price = $price - $discount;
}

• Florent: What have tried? Can you add more details?

Answer 1

Some simple logic will save you from all that (error-prone) writing. For instance:

if ($qty >= 6)
{
 if ($qty >= 21)
 $leg_directory_discount = 1.5;
 elseif ($qty >=11)
 $leg_directory_discount = 1.0;
 else
 $leg_directory_discount = 0.5;
}
else
 $leg_directory_discount = 0.0;

• Sven: Overly complicated, I'd say. How do you integrate a new discount for three products at 0.2 easily?

Answer 2

I like the idea of putting the discount steps into an array, but stating a discount for every possible quantity seems too much.

$leg_directory_discount = array(
 0 => 0,
 6 => .50,
 11 => 1,
 21 => 1.5,
);

This is the discount configuration - can later be stored in a config file or database.

This function gets the discount to be used:

function getDiscount($qty, $leg_directory_discount) {
 $return = 0;
 foreach ($leg_directory_discount as $amount => $discount) {
 if ($qty >= $amount) {
 $return = $discount;
 }
 }
 return $discount;
}

Answer 3

You could use a switch statement as well:

switch (true) {
 case ($price <=5):
 $discount = 0.0;
 break;
 case ($price <= 10):
 $discount = 0.5;
 break;
 case ($price <= 20):
 $discount = 1.0;
 break;
 default:
 $discount = 1.5;
 break;
}

Also your final price could be reduced to $price = $price * (100 - $discount) / 100;

• Sven: Your switch statement looks bogus. Shouldn't it be at least switch (true) if you want to evaluate on every case line. You might get along because $price evaluates to true most of the time. I would try to avoid switch nonetheless - makes code overcomplicated in the long run.
• Jeffory J. Beckers: @Sven: your probably right, edited per your comment.