Question

A mail-order house sells five products whose retail prices are as follows: Product \(1, \$ 2.98\) product \(2, \$ 4.50 ;\) product \(3, \$ 9.98 ;\) product \(4, \$ 4.49\) and product \(5, \$ 6.87 .\) Write an application that reads a series of pairs of numbers as follows: a) product number b) quantity sold Your program should use a switch statement to determine the retail price for each product. It should calculate and display the total retail value of all products sold. Use a sentinel-controlled loop to determine when the program should stop looping and display the final results.

Short answer

Calculate and accumulate the retail value of products sold using a loop and switch statement, and display the total when input ends.

Step-by-step solution

Initialize Variables and Accept Input

Begin the program by initializing a variable to store the total retail value of all products sold (e.g., `total_retail_value = 0`). Prompt the user to enter pairs of numbers representing the product number and quantity sold. Use a loop that continues until a sentinel value is entered to end the input (e.g., a product number of `0`).

Check Product Number Using Switch Statement

Inside the loop, use a switch statement (or a series of if-else blocks) to match the product number entered by the user to its corresponding retail price. Make sure to handle cases for product numbers 1 to 5 and include a default case to handle invalid product numbers.

Calculate Retail Value for Each Product

For each valid product number entered, calculate the retail value of the sale by multiplying the retail price by the quantity sold. Add this value to the `total_retail_value` variable. For example, if the user inputs product number `1` and quantity `3`, add `3 * 2.98` to `total_retail_value`.

Prompt For More Input or End

After processing the current input, prompt the user again to enter another pair of numbers or the sentinel value to end. Continue processing input in the loop until the sentinel value is entered.

Display Total Retail Value

Once the loop exits after receiving the sentinel value, display the total retail value of all products sold stored in `total_retail_value`. This final total should consider all inputs from the session.

Key concepts

Sentinel-controlled loop

Sentinel-controlled loops are a fundamental concept in programming that helps manage repetitive tasks in an efficient manner. Think of a sentinel as a signal that tells the loop when to stop running. In this exercise, we're processing product sales until the user indicates they are finished by entering a special sentinel value: product number `0`. This value doesn’t correspond to any real product and is used solely to stop the loop.

One major advantage of using a sentinel-controlled loop is that it offers flexibility in the number of iterations. The loop continues processing the input until the sentinel value is encountered, without requiring us to know beforehand how many products will be entered. This makes it especially useful for applications like sales processing, where the number of items sold can vary greatly.

• Initialize your loop with a condition that checks for the sentinel value.
• Continue processing input within the loop.
• Ensure that every input sequence checks for the sentinel before proceeding.

Understanding and correctly implementing a sentinel can prevent endless loops and ensure the program terminates gracefully once the task is completed.

Retail price calculation

Calculating the retail price involves determining the total cost of items sold, based on their individual prices and the quantities sold. For this task, each product has a specific price associated with a product number. The concept here is straightforward but crucial, as it's the heart of the sales tracking mechanism.

Whenever a product number paired with a quantity sold is inputted, we multiply the quantity by the product’s retail price to calculate the value of that sale. This calculated amount is then summed to find the total retail value for all sales.

• Use a switch statement to map product numbers to their respective prices.
• Perform the multiplication of price and quantity to get the sale value.
• Accumulate the sale values to keep a running total.

By accurately keeping track of each sale, businesses can assess their total revenue and make informed inventory and sales strategies decisions.

Product number handling

Product number handling is vital for ensuring that input data is accurate and used correctly within a program. In this exercise, product numbers serve as identifiers that help in associating specific products with their respective prices.

When implementing product number handling, it's important to account for valid and invalid product numbers. A switch statement (or series of if-else statements) is an excellent choice for mapping product numbers to prices. Each product number corresponds to a price, and any entry that isn't between 1 and 5 can be flagged as invalid.

• Verify input by checking if the product number falls within the expected range.
• Use a switch statement to handle valid product numbers efficiently.
• Include a default case to manage invalid inputs and prompt the user for correct data.

Having robust product number handling ensures only valid sales are processed, preventing errors in calculating total retail value and maintaining data integrity throughout the transaction process.