Variadic parameters in Swift - Mini Project: Build & Apply

Using Variadic Parameters in Swift

📖 Scenario: You are creating a simple Swift program to calculate the total price of items bought in a store. The number of items can vary each time.

🎯 Goal: Build a Swift function that uses variadic parameters to accept any number of item prices and calculate their total.

📋 What You'll Learn

Create a function named calculateTotal that takes a variadic parameter of type Double named prices.

Inside the function, calculate the sum of all prices.

Return the total sum as a Double.

Call the function with multiple price values and print the result.

💡 Why This Matters

🌍 Real World

Variadic parameters let you write flexible functions that can handle any number of inputs, like calculating totals for shopping carts or processing multiple user inputs.

💼 Career

Understanding variadic parameters is useful for writing clean, reusable code in Swift apps, especially when dealing with lists of data where the count can change.

1

Create the function with variadic parameter

Write a Swift function named calculateTotal that takes a variadic parameter called prices of type Double. The function should return a Double. Do not add any code inside the function yet.

Swift

func calculateTotal(prices: Double...) -> Double {
    // Your code here
}

Need a hint?

Use Double... to declare a variadic parameter named prices.

2

Add a variable to hold the total sum

Inside the calculateTotal function, create a variable named total and set it to 0.0 to hold the sum of prices.

Swift

func calculateTotal(prices: Double...) -> Double {
    var total = 0.0
    // Your code here
}

Need a hint?

Declare total as a Double variable initialized to 0.0.

3

Sum all prices using a for loop

Use a for loop with variable price to iterate over prices inside the calculateTotal function. Add each price to the total variable.

Swift

func calculateTotal(prices: Double...) -> Double {
    var total = 0.0
    for price in prices {
        // Your code here
    }
    return 0.0
}

Need a hint?

Use for price in prices to loop through all prices and add each to total.

4

Return the total and print the result

Change the return statement to return the total variable. Then, call calculateTotal with the prices 10.5, 20.0, and 5.25. Print the result using print.

Swift

func calculateTotal(prices: Double...) -> Double {
    var total = 0.0
    for price in prices {
        total += price
    }
    return total
}

// Call the function and print the result
// Your code here

Need a hint?

Return total from the function. Call calculateTotal(prices: 10.5, 20.0, 5.25) and print the result.