How to Reverse an Array in Lua?

Using a Loop

One of the simplest and most straightforward ways to reverse an array in Lua is by using a loop. You can iterate through the array in a backward direction and construct a new reversed array. Here's an example:

function reverseArray(arr)
    local reversed = {}
    for i = #arr, 1, -1 do
        table.insert(reversed, arr[i])
    end
    return reversed
end

local myArray = {1, 2, 3, 4, 5}
local reversedArray = reverseArray(myArray)

for _, value in ipairs(reversedArray) do
    print(value)
end

Output:

5
4
3
2
1

Using the table.remove() Function

Lua provides the table.remove() function, which can be used to reverse an array in place. By removing elements from the end of the array and inserting them at the beginning, you can reverse the array directly. Here's an example:

function reverseArrayInPlace(arr)
    local n = #arr
    for i = 1, math.floor(n / 2) do
        arr[i], arr[n - i + 1] = arr[n - i + 1], arr[i]
    end
end

local myArray = {1, 2, 3, 4, 5}
reverseArrayInPlace(myArray)

for _, value in ipairs(myArray) do
    print(value)
end

Output:

5
4
3
2
1

Using a Stack

Another approach to reversing an array in Lua is by using a stack. You can push the elements of the array onto the stack in their original order and then pop them to construct the reversed array. Here's an example:

function reverseArrayWithStack(arr)
    local reversed = {}
    local stack = {}

    for _, value in ipairs(arr) do
        table.insert(stack, value)
    end

    while #stack > 0 do
        table.insert(reversed, table.remove(stack))
    end

    return reversed
end

local myArray = {1, 2, 3, 4, 5}
local reversedArray = reverseArrayWithStack(myArray)

for _, value in ipairs(reversedArray) do
    print(value)
end

Output:

5
4
3
2
1