The functions in the previous exercises produced output via println() statements contained within its code body; however, we also have the ability to return a value from a function.

A return statement returns a value from a function and passes it back to where the function was invoked. This value can then be used throughout our program.

If we want a function to return a value, we must add the return type to the function header as well as a return statement in the body. Take a look at the following example where we create a function that takes in a list of Ints and returns an Int value:

fun listSum(myList: List<Int>): Int { var sum = 0 // iterate through each value and add it to sum for (i in myList) { sum += i } // return statement return sum }
  • The return type describes the data type of the value being returned and is stated after the parentheses and a colon : in the function header.
  • The keyword return is used to declare a return statement. In this case, sum is the value being returned.
  • Any lines of code that exist after the return statement will not be executed.

Previously, we invoked functions by calling them on their own line of code; however, we can also invoke a function and assign it to a variable for later use.

For example, we can set total to the return value of listSum() after sending it a list of Int values (billsToPay):

var billsToPay = mutableListOf(44, 29, 104, 79) // Set total to the return value of listSum(). var total = listSum(billsToPay) println("Your bill total is $total dollars.")

This will output the following:

Your bill total is 256 dollars.



Following a recipe for vanilla cake, you are asked to add .75 ounces of vanilla extract; however, you only have a teaspoon to measure the ingredients.

Create a function called ozToTsp() that takes a Double type argument named oz and returns a Double type value.

Inside the function, create a variable tsp whose value is oz multiplied by 6. Use a return statement to return the value of tsp.


Inside main(), create a variable called tspNeeded and set its value to ozToTsp() with an argument of .75.

Use println() and a String template to output the following statement:

You will need [tspNeeded] tsp of vanilla extract for this recipe.

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