LESSON 158 OF 409 · PROJECTS: EVERYDAY PROGRAMS

Shopping Cart V2 - Tax and Discount in C++

Practice

Add a discount and sales tax to a single-item purchase using integer math.

You start with:

string item = "Coffee Mug";
int price = 12;
int quantity = 3;
int tax_rate = 8;
int discount = 5;

Build:

Subtotal: $36
Discount: $5
Tax: $2
Total: $33

Rules:

subtotal = price * quantity.
after_discount = subtotal - discount (the discount is a flat amount taken off before tax).
tax = after_discount * tax_rate / 100 (integer division, so the result is rounded down). The tax is charged on the discounted amount.
total = after_discount + tax.
Build four lines (Subtotal, Discount, Tax, Total) and join them with a newline "\n" into one string result, then print it with cout << result << endl.

Compute the four numbers (subtotal, after_discount, tax, total) before formatting.

Use to_string(...) to turn each number into text before concatenating it to a string.

C++'s int / int truncates, so after_discount * tax_rate / 100 already rounds down.

string item = "Coffee Mug";
int price = 12;
int quantity = 3;
int tax_rate = 8;
int discount = 5;

int subtotal = price * quantity;
int after_discount = subtotal - discount;
int tax = after_discount * tax_rate / 100;
int total = after_discount + tax;
string line1 = "Subtotal: $" + to_string(subtotal);
string line2 = "Discount: $" + to_string(discount);
string line3 = "Tax: $" + to_string(tax);
string line4 = "Total: $" + to_string(total);
string result = line1 + "\n" + line2 + "\n" + line3 + "\n" + line4;
cout << result << endl;

STEP 1 OF 10

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Shopping Cart V2 - Tax and Discount in C++

Shopping Cart V2 in C++