Subtracting percentage of value in php

Question

I am writing something similar to the function of a coupon code and I want to be able to process both the set quantity codes and percentage amounts.

My code is as follows:

$amount = "25"; // amount of discount $percent = "yes"; // whether coupon is (yes) a percentage, or (no) a flat amount if($percent == "yes"){ $newprice = ???????; // subtract $amount % of $price, from $price }else{ $newprice = $price - $amount; // if not a percentage, subtract from price outright } 

Im looking for google when you read this looking for a solution, but I thought id would post it here to help others who might run into the same problem.

Answer 1

How about this?

 $newprice = $price * ((100-$amount) / 100); 

Answer 2

In addition to basic math, I also suggest that you use round () to force the result to have 2 decimal places.

 $newprice = round($price * ((100-$amount) / 100), 2); 

Thus, the price of $ 24.99, discounted by 25%, will be 18.7425, which is then rounded to 18.74

Answer 3

I would go with

 $newprice = $price - ($price * ($amount/100)) 

Answer 4

To get the percentage of the number, you can simply multiply by the decimal fraction of the percentage that you want. For example, if you want something to be 25% higher, you can multiply by 0.75 because you want it to cost 75% of its original price. To implement this for your example, you want to do something like:

 if($percent == "yes"){ $newprice = ($price * ((100-$amount) / 100)); // subtract $amount % of $price, from $price }else{ $newprice = $price - $amount; // if not a percentage, subtract from price outright } 

What it is:

• Subtract a percentage discount of 100 to give us a percentage of the original price.
• Divide this number by 100 to give it to us in decimal form (for example, 0.75).
• Multiply the original price by the calculated decimal number above to get a new price.

Answer 5

 $price -= ($percent == 'yes' ? ($price * ($amount / 100)) : $amount);