Doug Harper

While working on fundamentals of functions I ran across Variadic Parameters, which I’ve seen before but make more sense now.

A variadic parameter accepts one or more values, which makes it very useful. I can easily think of many situations when you’ll need to enter data without knowing the number of data items -> like an estimator, recipes, sales figures, etc…

Food Truck Excercise

The owner of a Food Truck wants keep track of daily total sales amounts. The truck’s crew should enter each sale as it occurs.

First Attempt

func totalSales(day: String = "Monday", saleAmount: Double...) {
    
    var sum = 0.0

    for sale in saleAmount {
        sum += sale
    }

  print("The total sales for \(day) is \(sum)")

}

let mondaysSales = totalSales(saleAmount: 34.56, 47.56)
let tuesdaysSales = totalSales("Tuesday", saleAmount: 23.45, 67.21, 45.21)

I used a default parameter for day simple as an excercise since I’m practicing with parameters. saleAmount: Double... is the variadic parameter and allows me to enter any number of sales into my function i.e. 2 sales on Monday, 3 sales on Tuesday.

Refactor #1

enum DayOfTheWeek{
  case Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday
}
  
func totalSales(day: DayOfTheWeek, saleAmount: Double...) {
var sum = 0.0

for sale in saleAmount {
    sum += sale
}

print("The total sales for \(day) is \(sum)")

}

totalSales(.Monday, saleAmount: 56.78, 34.56)
totalSales(.Tuesday, saleAmount: 12.45, 45.78, 35.89)
totalSales(.Wednesday, saleAmount: 12.45, 467.45, 25.78, 72.98, 109.87)

Instead of creating 7 let or vars I set up an Enum for DaysOfTheWeek and threw it in place of my default parameter, which makes the code look much cleaner and easier to understand.