Returning Values from Tables

A common need in many data structures is to return values. This article will cover searching a table using pairs() or ipairs() for half of any table element, such as the key or value, to find and return the other half.

The example uses an array listing ships waiting to be repaired. ipairs() is used to return a ship's place in line.

local shipToFind = "Void Racer"

-- Ships waiting for repair
local waitingShips = {"Battle Sun", "Void Racer", "The Big Slow"}

-- Get place in line
local function getPlaceInLine(shipName)
	for placeInLine,ship in ipairs(waitingShips) do
		if ship == shipName then
			return placeInLine
		end
	end
end

--Print place in line
local placeInLine = getPlaceInLine(shipToFind)
print("Your place in line is " .. placeInLine)

Dictionary Search Example

Have you ever searched for a lost pet in house going room by room? On your own code a function to search through a dictionary named house to see which room holds a lost puppy.

1. Copy the dictionary below to act as the house.

   local house = {
       kitchen = "pile of Junk",
       livingRoom = "kitten",
       bedroom1 = "nobody there",
       bedroom2 = "puppy",
   }

2. Create a new function called findPet() to search the dictionary. Include parameters for what dictionary to search, and what value to search for.

3. Use pairs() to iterate through the dictionary. Try coding your own before checking your work in the solution below.

   local function findPet(whereToSearch, searchFor)
     for place, value in pairs(whereToSearch) do
   
     end
   end

4. As the for loop iterates through the dictionary, use return to pass back the room where the pet was found.

   local function findPet(whereToSearch, searchFor)
     for place, value in pairs(whereToSearch) do
       if value == searchFor then
         return place
       end
     end
   end