C++ Program To Calculate The Restaurant Bill Including Tax And Tip

Introduction

Calculating the total cost of a restaurant meal can sometimes be tricky, especially when factoring in tax and tip. In this article, you will learn how to write a simple C++ program that accurately calculates a restaurant bill, including both tax and tip, providing a clear final amount.

Problem Statement

When dining out, guests often need to calculate the final bill, which involves adding sales tax and a gratuity (tip) to the base cost of the meal. Manually calculating these percentages can be error-prone and time-consuming, especially for complex orders or when splitting bills. A program is needed to automate this process, ensuring accuracy and efficiency.

Example

Here's a quick look at how the calculation will appear:

If your base meal cost is $50.00, with a 7% tax and a 15% tip:

• Tax amount: $3.50
• Subtotal (meal + tax): $53.50
• Tip amount (15% of $53.50): $8.03
• Total bill: $61.53

Background & Knowledge Prerequisites

To understand and implement this C++ program, you should be familiar with the following basic C++ concepts:

• Variables: Declaring and using variables to store numerical data (e.g., double for decimal values).
• Input/Output (I/O): Using std::cin to get input from the user and std::cout to display output.
• Arithmetic Operations: Performing addition, subtraction, multiplication, and division.
• Basic Control Flow: Sequential execution of statements.
• Header Files: Including necessary libraries like iostream for I/O and iomanip for formatting.

Use Cases or Case Studies

Calculating restaurant bills with tax and tip is a common task with several practical applications:

• Individual Diners: Quickly determine the total cost of a meal and avoid manual calculations.
• Group Diners: Calculate individual contributions to a shared bill, factoring in their share of the base cost, tax, and tip.
• Restaurant Staff: Provide customers with a quick and accurate estimate of their final bill.
• Budgeting Tools: Integrate into personal finance applications to track dining expenses.
• Educational Demonstrations: Serve as a basic programming example to teach fundamental C++ concepts like variables, input, and arithmetic.

Solution Approaches

C++ Program for Restaurant Bill Calculation

This approach involves creating a straightforward C++ program that prompts the user for the base meal cost, tax rate, and tip percentage, then computes and displays the total bill.

Summary: Read the base meal cost, tax rate, and tip percentage from the user, then calculate the tax amount, tip amount, and the final total bill.

Code Example:

// Restaurant Bill Calculator
#include <iostream> // For input/output operations (cin, cout)
#include <iomanip>  // For output formatting (setprecision, fixed)

using namespace std;

int main() {
    // Step 1: Declare variables to store inputs and calculated values
    double baseMealCost;
    double taxRate;       // as a percentage, e.g., 7 for 7%
    double tipPercentage; // as a percentage, e.g., 15 for 15%
    double taxAmount;
    double tipAmount;
    double totalBill;

    // Step 2: Get input from the user for base meal cost
    cout << "Enter the base cost of the meal: $";
    cin >> baseMealCost;

    // Step 3: Get input for tax rate
    cout << "Enter the tax rate (e.g., 7 for 7%): ";
    cin >> taxRate;

    // Step 4: Get input for tip percentage
    cout << "Enter the tip percentage (e.g., 15 for 15%): ";
    cin >> tipPercentage;

    // Step 5: Convert percentages to decimal for calculation
    // Example: 7% becomes 0.07, 15% becomes 0.15
    double decimalTaxRate = taxRate / 100.0;
    double decimalTipPercentage = tipPercentage / 100.0;

    // Step 6: Calculate the tax amount
    taxAmount = baseMealCost * decimalTaxRate;

    // Step 7: Calculate the tip amount (usually on the meal cost + tax)
    // This program calculates tip on (base cost + tax).
    tipAmount = (baseMealCost + taxAmount) * decimalTipPercentage;

    // Step 8: Calculate the total bill
    totalBill = baseMealCost + taxAmount + tipAmount;

    // Step 9: Display the results with two decimal places for currency
    cout << fixed << setprecision(2); // Set output to fixed-point notation with 2 decimal places

    cout << "\\n--- Bill Details ---" << endl;
    cout << "Base Meal Cost: $" << baseMealCost << endl;
    cout << "Tax Rate (" << taxRate << "%): $" << taxAmount << endl;
    cout << "Tip (" << tipPercentage << "%): $" << tipAmount << endl;
    cout << "--------------------" << endl;
    cout << "Total Bill:     $" << totalBill << endl;

    return 0; // Indicate successful execution
}

Run

Sample Output:

Enter the base cost of the meal: $50
Enter the tax rate (e.g., 7 for 7%): 7
Enter the tip percentage (e.g., 15 for 15%): 15

--- Bill Details ---
Base Meal Cost: $50.00
Tax Rate (7.00%): $3.50
Tip (15.00%): $8.03
--------------------
Total Bill:     $61.53

Stepwise Explanation:

1. Include Headers: The program starts by including iostream for input/output and iomanip for output formatting (specifically setprecision and fixed).
2. Declare Variables: double variables are declared to store the baseMealCost, taxRate, tipPercentage, and the calculated taxAmount, tipAmount, and totalBill. Using double ensures accuracy for decimal currency values.
3. Get User Input: The program prompts the user to enter the base cost of the meal, the tax rate (as a percentage, e.g., 7 for 7%), and the tip percentage (e.g., 15 for 15%). std::cin reads these values into the respective variables.
4. Convert Percentages: The input tax rate and tip percentage, which are whole numbers (e.g., 7 for 7%), are converted to their decimal equivalents by dividing them by 100.0. This is crucial for correct multiplication in subsequent calculations.
5. Calculate Tax Amount: The taxAmount is calculated by multiplying the baseMealCost by the decimalTaxRate.
6. Calculate Tip Amount: The tipAmount is calculated by applying the decimalTipPercentage to the subtotal (which is baseMealCost + taxAmount). This is a common practice for calculating tips on the total amount after tax.
7. Calculate Total Bill: The totalBill is the sum of baseMealCost, taxAmount, and tipAmount.
8. Format and Display Results:
   • std::fixed and std::setprecision(2) are used to format the output currency values to exactly two decimal places, which is standard for monetary values.

The program then prints a clear breakdown of the base cost, calculated tax, calculated tip, and the final total bill.

1. Return 0: The main function returns 0 to indicate successful execution of the program.

Conclusion

Accurately calculating restaurant bills, including tax and tip, is a practical application of basic programming concepts. By using C++ to automate this process, we can ensure precise totals and reduce the potential for manual errors. This simple program demonstrates how variables, user input, arithmetic operations, and output formatting can be combined to solve common real-world problems.

Summary

• Problem: Manual calculation of restaurant bills with tax and tip is error-prone.
• Solution: A C++ program automates bill calculation.
• Inputs: Base meal cost, tax rate, tip percentage.
• Calculations:
• Tax amount = Base Cost \* (Tax Rate / 100)
• Tip amount = (Base Cost + Tax Amount) \* (Tip Percentage / 100)
• Total Bill = Base Cost + Tax Amount + Tip Amount
• Output: Formatted display of base cost, tax amount, tip amount, and total bill.
• Key C++ Features: double for decimals, std::cin for input, std::cout for output, std::fixed and std::setprecision for currency formatting.