LESSON 161 OF 409 · PROJECTS: EVERYDAY PROGRAMS

Shopping Cart V5 - Coupon Codes in C++

Practice

Use a map as a fast lookup table for coupon discounts.

You start with:

int subtotal = 100;
string coupon = "SAVE20";
unordered_map<string, int> coupons = {{"SAVE10", 10}, {"SAVE20", 20}, {"SAVE50", 50}};

Build:

Total: $80

Rules:

Look up coupon in coupons. If it is there, its value is the discount; if it is not (an unknown code), the discount is 0.
total = subtotal - discount.
Build the text "Total: $<total>" (e.g. "Total: $80"; an unknown coupon would give "Total: $100").
Store it in result, then print it with cout << result << endl.

Use coupons.count(coupon) ? coupons[coupon] : 0: count tells you whether the key is present.

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

int subtotal = 100;
string coupon = "SAVE20";
unordered_map<string, int> coupons = {{"SAVE10", 10}, {"SAVE20", 20}, {"SAVE50", 50}};

int discount = coupons.count(coupon) ? coupons[coupon] : 0;
int total = subtotal - discount;
string result = "Total: $" + to_string(total);
cout << result << endl;

STEP 1 OF 4

Guided

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Shopping Cart V5 - Coupon Codes in C++

Shopping Cart V5 in C++