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Replace magic numbers and strings with named constants across all implementations #25

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b42754f
Initial plan
Copilot Nov 21, 2025
4dca959
Fix magic strings and numbers in Python, Java, and TypeScript impleme…
Copilot Nov 21, 2025
0800cdf
Complete magic strings and numbers fixes for all language implementat…
Copilot Nov 21, 2025
4fc52b6
Fix PHP to use string constants for discount descriptions
Copilot Nov 21, 2025
a43490e
Final summary - Magic strings and numbers eliminated
Copilot Nov 21, 2025
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1 change: 1 addition & 0 deletions _codeql_detected_source_root
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@@ -0,0 +1 @@
.
41 changes: 27 additions & 14 deletions c/src/supermarket.c
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Expand Up @@ -3,6 +3,19 @@
#include <stdio.h>
#include "supermarket.h"

// Constants for magic numbers
#define DEFAULT_ITEM_QUANTITY 1.0
#define TWO_FOR_AMOUNT_QUANTITY 2
#define THREE_FOR_TWO_QUANTITY 3
#define FIVE_FOR_AMOUNT_QUANTITY 5
#define PERCENTAGE_DIVISOR 100.0

// Constants for discount description strings
#define THREE_FOR_TWO_DESCRIPTION "3 for 2"
#define TWO_FOR_FORMAT "2 for %f"
#define FOR_FORMAT "%d for %f"
#define PERCENT_OFF_FORMAT "%.0f%% off"

struct product_t* product_create(char* name, enum unit unit) {
struct product_t* product = malloc(sizeof(*product));
strncpy(product->name, name, sizeof(product->name) - 1);
Expand Down Expand Up @@ -76,36 +89,36 @@ void handle_offers(struct cart_t* cart, struct receipt_t* receipt, struct specia
int x = 1;

if (offer->type == ThreeForTwo) {
x = 3;
x = THREE_FOR_TWO_QUANTITY;
} else if (offer->type == TwoForAmount) {
x = 2;
if (quantityAsInt >= 2) {
double total = offer->argument * (quantityAsInt / x) + quantityAsInt % 2 * unitPrice;
x = TWO_FOR_AMOUNT_QUANTITY;
if (quantityAsInt >= TWO_FOR_AMOUNT_QUANTITY) {
double total = offer->argument * (quantityAsInt / x) + quantityAsInt % TWO_FOR_AMOUNT_QUANTITY * unitPrice;
double discountN = unitPrice * quantity - total;
char description[MAX_NAME_LENGTH];
sprintf(description, "2 for %f", offer->argument);
sprintf(description, TWO_FOR_FORMAT, offer->argument);
discount = discount_create(description, -discountN, &product);
}
} if (offer->type == FiveForAmount) {
x = 5;
x = FIVE_FOR_AMOUNT_QUANTITY;
}
int numberOfXs = quantityAsInt / x;
if (offer->type == ThreeForTwo && quantityAsInt > 2) {
double discountAmount = quantity * unitPrice - ((numberOfXs * 2 * unitPrice) + quantityAsInt % 3 * unitPrice);
if (offer->type == ThreeForTwo && quantityAsInt > TWO_FOR_AMOUNT_QUANTITY) {
double discountAmount = quantity * unitPrice - ((numberOfXs * TWO_FOR_AMOUNT_QUANTITY * unitPrice) + quantityAsInt % THREE_FOR_TWO_QUANTITY * unitPrice);
char description[MAX_NAME_LENGTH];
sprintf(description, "3 for 2");
sprintf(description, THREE_FOR_TWO_DESCRIPTION);
discount = discount_create(description, -discountAmount, &product);
}
if (offer->type == TenPercentDiscount) {
char description[MAX_NAME_LENGTH];
sprintf(description, "%.0f%% off", offer->argument);
discount = discount_create(description, -quantity * unitPrice * offer->argument / 100.0, &product);
sprintf(description, PERCENT_OFF_FORMAT, offer->argument);
discount = discount_create(description, -quantity * unitPrice * offer->argument / PERCENTAGE_DIVISOR, &product);

}
if (offer->type == FiveForAmount && quantityAsInt >= 5) {
double discountTotal = unitPrice * quantity - (offer->argument * numberOfXs + quantityAsInt % 5 * unitPrice);
if (offer->type == FiveForAmount && quantityAsInt >= FIVE_FOR_AMOUNT_QUANTITY) {
double discountTotal = unitPrice * quantity - (offer->argument * numberOfXs + quantityAsInt % FIVE_FOR_AMOUNT_QUANTITY * unitPrice);
char description[MAX_NAME_LENGTH];
sprintf(description, "%d for %f", x, offer->argument);
sprintf(description, FOR_FORMAT, x, offer->argument);
discount = discount_create(description, -discountTotal, &product);
}
if (discount != NULL) {
Expand Down
36 changes: 23 additions & 13 deletions common-lisp/source/shopping-cart.lisp
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Expand Up @@ -2,6 +2,16 @@

(in-package :supermarket-receipt)

;;; Constants for magic numbers
(defconstant +default-item-quantity+ 1.0)
(defconstant +two-for-amount-quantity+ 2)
(defconstant +three-for-two-quantity+ 3)
(defconstant +five-for-amount-quantity+ 5)
(defconstant +percentage-divisor+ 100.0)

;;; Constants for discount description strings
(defconstant +three-for-two-description+ "3 for 2")

(defclass shopping-cart ()
((items :initform nil
:type list
Expand All @@ -11,7 +21,7 @@
:accessor shopping-cart-product-quantities)))

(defmethod add-item ((a-cart shopping-cart) (an-item product))
(add-item-quantity a-cart an-item 1.0))
(add-item-quantity a-cart an-item +default-item-quantity+))

(defmethod add-item-quantity ((a-cart shopping-cart) (an-item product) (a-quantity single-float))
(push (make-instance 'product-quantity
Expand All @@ -35,39 +45,39 @@
(x 1)
(the-offer-type (offer-type offer-for-product)))
(if (eq the-offer-type 'three-for-two)
(setf x 3)
(setf x +three-for-two-quantity+)
(when (eq the-offer-type 'two-for-amount)
(setf x 2)
(when (>= floored-quantity 2)
(setf x +two-for-amount-quantity+)
(when (>= floored-quantity +two-for-amount-quantity+)
(let* ((total (+ (* (offer-argument offer-for-product) (floor (/ floored-quantity x)))
(* (mod floored-quantity 2) a-unit-price)))
(* (mod floored-quantity +two-for-amount-quantity+) a-unit-price)))
(discount-n (- (* a-unit-price a-quantity) total)))
(setf a-discount (make-instance 'discount
:product a-product
:description (format nil "2 for ~S" (offer-argument offer-for-product))
:amount (- discount-n)))))))
(when (eq the-offer-type 'five-for-amount)
(setf x 5))
(setf x +five-for-amount-quantity+))
(let ((number-of-x (floor (/ floored-quantity x))))
(when (and (eq the-offer-type 'three-for-two)
(> floored-quantity 2))
(> floored-quantity +two-for-amount-quantity+))
(let ((discount-amount (- (* a-quantity a-unit-price)
(+ (* number-of-x 2 a-unit-price)
(* (mod floored-quantity 3) a-unit-price)))))
(+ (* number-of-x +two-for-amount-quantity+ a-unit-price)
(* (mod floored-quantity +three-for-two-quantity+) a-unit-price)))))
(setf a-discount (make-instance 'discount
:product a-product
:description "3 for 2"
:description +three-for-two-description+
:amount (- discount-amount)))))
(when (eq the-offer-type 'ten-percent-discount)
(setf a-discount (make-instance 'discount
:product a-product
:description (format nil "~S % off" (offer-argument offer-for-product))
:amount (/ (* (- a-quantity) a-unit-price (offer-argument offer-for-product)) 100.0))))
:amount (/ (* (- a-quantity) a-unit-price (offer-argument offer-for-product)) +percentage-divisor+))))
(when (and (eq the-offer-type 'five-for-amount)
(>= floored-quantity 5))
(>= floored-quantity +five-for-amount-quantity+))
(let ((discount-total (- (* a-quantity a-unit-price)
(+ (* (offer-argument offer-for-product) number-of-x)
(* (mod floored-quantity 5) a-unit-price)))))
(* (mod floored-quantity +five-for-amount-quantity+) a-unit-price)))))
(setf a-discount (make-instance 'discount
:product a-product
:description (format nil "~S for ~S" x (offer-argument offer-for-product))
Expand Down
43 changes: 29 additions & 14 deletions cpp/src/ShoppingCart.cpp
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@@ -1,5 +1,20 @@
#include "ShoppingCart.h"

// Constants for magic numbers
namespace {
constexpr double DEFAULT_ITEM_QUANTITY = 1.0;
constexpr int TWO_FOR_AMOUNT_QUANTITY = 2;
constexpr int THREE_FOR_TWO_QUANTITY = 3;
constexpr int FIVE_FOR_AMOUNT_QUANTITY = 5;
constexpr double PERCENTAGE_DIVISOR = 100.0;

// Constants for discount description strings
const std::string THREE_FOR_TWO_DESCRIPTION = "3 for 2";
const std::string TWO_FOR_PREFIX = "2 for ";
const std::string FOR_SEPARATOR = " for ";
const std::string PERCENT_OFF_SUFFIX = "% off";
}

void addItemQuantity(const Product& product, double quantity);

std::vector<ProductQuantity> ShoppingCart::getItems() const {
Expand All @@ -11,7 +26,7 @@ std::map<Product, double> ShoppingCart::getProductQuantities() const {
}

void ShoppingCart::addItem(const Product& product) {
addItemQuantity(product, 1.0);
addItemQuantity(product, DEFAULT_ITEM_QUANTITY);
}

void ShoppingCart::addItemQuantity(const Product& product, double quantity) {
Expand All @@ -35,28 +50,28 @@ void ShoppingCart::handleOffers(Receipt& receipt, std::map<Product, Offer> offer
int x = 1;

if (offer.getOfferType() == SpecialOfferType::ThreeForTwo) {
x = 3;
x = THREE_FOR_TWO_QUANTITY;
} else if (offer.getOfferType() == SpecialOfferType::TwoForAmount) {
x = 2;
if (quantityAsInt >= 2) {
double total = offer.getArgument() * (quantityAsInt / x) + quantityAsInt % 2 * unitPrice;
x = TWO_FOR_AMOUNT_QUANTITY;
if (quantityAsInt >= TWO_FOR_AMOUNT_QUANTITY) {
double total = offer.getArgument() * (quantityAsInt / x) + quantityAsInt % TWO_FOR_AMOUNT_QUANTITY * unitPrice;
double discountN = unitPrice * quantity - total;
discount = new Discount("2 for " + std::to_string(offer.getArgument()), -discountN, product);
discount = new Discount(TWO_FOR_PREFIX + std::to_string(offer.getArgument()), -discountN, product);
}
} if (offer.getOfferType() == SpecialOfferType::FiveForAmount) {
x = 5;
x = FIVE_FOR_AMOUNT_QUANTITY;
}
int numberOfXs = quantityAsInt / x;
if (offer.getOfferType() == SpecialOfferType::ThreeForTwo && quantityAsInt > 2) {
double discountAmount = quantity * unitPrice - ((numberOfXs * 2 * unitPrice) + quantityAsInt % 3 * unitPrice);
discount = new Discount("3 for 2", -discountAmount, product);
if (offer.getOfferType() == SpecialOfferType::ThreeForTwo && quantityAsInt > TWO_FOR_AMOUNT_QUANTITY) {
double discountAmount = quantity * unitPrice - ((numberOfXs * TWO_FOR_AMOUNT_QUANTITY * unitPrice) + quantityAsInt % THREE_FOR_TWO_QUANTITY * unitPrice);
discount = new Discount(THREE_FOR_TWO_DESCRIPTION, -discountAmount, product);
}
if (offer.getOfferType() == SpecialOfferType::TenPercentDiscount) {
discount = new Discount(std::to_string(offer.getArgument()) + "% off", -quantity * unitPrice * offer.getArgument() / 100.0, product);
discount = new Discount(std::to_string(offer.getArgument()) + PERCENT_OFF_SUFFIX, -quantity * unitPrice * offer.getArgument() / PERCENTAGE_DIVISOR, product);
}
if (offer.getOfferType() == SpecialOfferType::FiveForAmount && quantityAsInt >= 5) {
double discountTotal = unitPrice * quantity - (offer.getArgument() * numberOfXs + quantityAsInt % 5 * unitPrice);
discount = new Discount(std::to_string(x) + " for " + std::to_string(offer.getArgument()), -discountTotal, product);
if (offer.getOfferType() == SpecialOfferType::FiveForAmount && quantityAsInt >= FIVE_FOR_AMOUNT_QUANTITY) {
double discountTotal = unitPrice * quantity - (offer.getArgument() * numberOfXs + quantityAsInt % FIVE_FOR_AMOUNT_QUANTITY * unitPrice);
discount = new Discount(std::to_string(x) + FOR_SEPARATOR + std::to_string(offer.getArgument()), -discountTotal, product);
}
if (discount != nullptr)
receipt.addDiscount(*discount);
Expand Down
41 changes: 27 additions & 14 deletions csharp-ms/SupermarketReceipt/ShoppingCart.cs
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Expand Up @@ -4,6 +4,19 @@ namespace SupermarketReceipt
{
public class ShoppingCart
{
// Constants for magic numbers
private const double DefaultItemQuantity = 1.0;
private const int TwoForAmountQuantity = 2;
private const int ThreeForTwoQuantity = 3;
private const int FiveForAmountQuantity = 5;
private const double PercentageDivisor = 100.0;

// Constants for discount description strings
private const string ThreeForTwoDescription = "3 for 2";
private const string TwoForPrefix = "2 for ";
private const string ForSeparator = " for ";
private const string PercentOffSuffix = "% off";

private readonly List<ProductQuantity> _items = new List<ProductQuantity>();
private readonly Dictionary<Product, double> _productQuantities = new Dictionary<Product, double>();

Expand All @@ -15,7 +28,7 @@ public List<ProductQuantity> GetItems()

public void AddItem(Product product)
{
AddItemQuantity(product, 1.0);
AddItemQuantity(product, DefaultItemQuantity);
}


Expand Down Expand Up @@ -47,32 +60,32 @@ public void HandleOffers(Receipt receipt, Dictionary<Product, Offer> offers, Sup
var x = 1;
if (offer.OfferType == SpecialOfferType.ThreeForTwo)
{
x = 3;
x = ThreeForTwoQuantity;
}
else if (offer.OfferType == SpecialOfferType.TwoForAmount)
{
x = 2;
if (quantityAsInt >= 2)
x = TwoForAmountQuantity;
if (quantityAsInt >= TwoForAmountQuantity)
{
var total = offer.Argument * (quantityAsInt / x) + quantityAsInt % 2 * unitPrice;
var total = offer.Argument * (quantityAsInt / x) + quantityAsInt % TwoForAmountQuantity * unitPrice;
var discountN = unitPrice * quantity - total;
discount = new Discount(p, "2 for " + offer.Argument, -discountN);
discount = new Discount(p, TwoForPrefix + offer.Argument, -discountN);
}
}

if (offer.OfferType == SpecialOfferType.FiveForAmount) x = 5;
if (offer.OfferType == SpecialOfferType.FiveForAmount) x = FiveForAmountQuantity;
var numberOfXs = quantityAsInt / x;
if (offer.OfferType == SpecialOfferType.ThreeForTwo && quantityAsInt > 2)
if (offer.OfferType == SpecialOfferType.ThreeForTwo && quantityAsInt > TwoForAmountQuantity)
{
var discountAmount = quantity * unitPrice - (numberOfXs * 2 * unitPrice + quantityAsInt % 3 * unitPrice);
discount = new Discount(p, "3 for 2", -discountAmount);
var discountAmount = quantity * unitPrice - (numberOfXs * TwoForAmountQuantity * unitPrice + quantityAsInt % ThreeForTwoQuantity * unitPrice);
discount = new Discount(p, ThreeForTwoDescription, -discountAmount);
}

if (offer.OfferType == SpecialOfferType.TenPercentDiscount) discount = new Discount(p, offer.Argument + "% off", -quantity * unitPrice * offer.Argument / 100.0);
if (offer.OfferType == SpecialOfferType.FiveForAmount && quantityAsInt >= 5)
if (offer.OfferType == SpecialOfferType.TenPercentDiscount) discount = new Discount(p, offer.Argument + PercentOffSuffix, -quantity * unitPrice * offer.Argument / PercentageDivisor);
if (offer.OfferType == SpecialOfferType.FiveForAmount && quantityAsInt >= FiveForAmountQuantity)
{
var discountTotal = unitPrice * quantity - (offer.Argument * numberOfXs + quantityAsInt % 5 * unitPrice);
discount = new Discount(p, x + " for " + offer.Argument, -discountTotal);
var discountTotal = unitPrice * quantity - (offer.Argument * numberOfXs + quantityAsInt % FiveForAmountQuantity * unitPrice);
discount = new Discount(p, x + ForSeparator + offer.Argument, -discountTotal);
}

if (discount != null)
Expand Down
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