In the last lesson, you passed information into functions using parameters. In this lesson, you will learn how functions can send information back using return values. Instead of only printing inside a function, you will compute a result and return it so the caller can store it, print it, or use it later.

Explanation:

• The first two lines create data we will use: a table of country_costs and a list of selected countries.
• The function calculate_trip_cost(countries, costs) takes two parameters: a list of countries and a lookup table of costs.
• It initializes total_cost to 0, loops through the chosen countries with ipairs, and adds each country’s cost using costs[country].
• return total_cost sends the computed total back to whoever called the function. The function itself does not print.

Explanation:

• The function call produces a value. We store that value in trip_cost.
• We then print a readable message by concatenating the string with trip_cost using ...
• Returning a value lets you reuse it anywhere in your program, not just print it once.

In Lua, a function can return more than one value by separating them with commas in the return statement.

Explanation:

• The function min_and_max(a, b) compares two numbers and returns both the smaller and the larger value.
• When calling the function, you can assign each returned value to its own variable.
• This is useful when you want a function to provide more than one result at a time.

You learned how to:

• Compute a result inside a function and return it with return.
• Pass data into a function via parameters and get data back as a return value.
• Store that returned value in a variable and print it when needed.

Great work advancing from parameters to return values. Head to the practice section to apply these ideas and see how returning values makes your functions more powerful and reusable.