Lua Academy · Lesson

table.concat and table.move

Efficiently join arrays and copy table slices with built-in functions.

Lesson 2 of 413 steps

table.concat and table.move is a free Lua Academy lesson on CoddyKit. This is lesson 2 of 4. Any 3 lessons of this learning path are free to read in full — after that, CoddyKit PRO unlocks every lesson, plus hands-on practice with a built-in code editor and a 24/7 AI tutor. It is part of the Lua Academy learning path, and your progress syncs across the web and the CoddyKit app. The Lua Academy course includes 4 lessons in total.

table.concat Basics

table.concat(t, sep, i, j) joins array elements into a string. sep defaults to "".

Simple Join

Join an array of strings with a separator.

local fruits = {"apple", "banana", "cherry"}
print(table.concat(fruits, ", "))  -- apple, banana, cherry

Partial Join with i and j

Specify start and end indices to join a slice of the array.

local t = {"a", "b", "c", "d", "e"}
print(table.concat(t, "-", 2, 4))  -- b-c-d

Numbers in table.concat

Elements must be strings or numbers; other types cause an error. Convert with tostring first.

local nums = {1, 2, 3}
print(table.concat(nums, " + "))  -- 1 + 2 + 3

table.move Introduction

table.move(a1, f, e, t, a2) copies elements from table a1 (indices f..e) into table a2 starting at index t.

Copying a Slice

Copy elements 2 through 4 of one table into another.

local src = {10, 20, 30, 40, 50}
local dst = {}
table.move(src, 2, 4, 1, dst)
print(table.concat(dst, ", "))  -- 20, 30, 40

In-Place Shift

Use table.move with the same source and destination to shift elements within a table.

local t = {1, 2, 3, 4, 5}
table.move(t, 2, 5, 1)  -- shift left by 1
t[5] = nil

Appending a Slice

Append a slice of one table to the end of another efficiently.

local base = {"x", "y"}
local extra = {"a", "b", "c"}
table.move(extra, 1, #extra, #base + 1, base)
print(table.concat(base, ", "))

Cloning a Table with table.move

A shallow clone can be made by moving the entire table into a fresh table.

local original = {1, 2, 3}
local clone = {}
table.move(original, 1, #original, 1, clone)

Performance Benefit

table.move is implemented in C and is faster than a manual Lua loop for large slices, as it avoids interpreter overhead per element.

table.concat vs string.format

Use table.concat for joining arrays; use string.format for structured formatting of individual values.

table.move Question

What does table.move(src, 2, 4, 1, dst) do?

Answer it in the interactive lesson

Recap: concat & move

table.concat joins array elements into a string. table.move efficiently copies table slices in C. Both are essential for high-performance table manipulation.

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Frequently Asked Questions

Is the “table.concat and table.move” lesson free?

Yes — any 3 lessons of the Lua Academy learning path, including “table.concat and table.move”, are free to read in full here on the web. After that, CoddyKit PRO unlocks every lesson, plus interactive practice with a built-in code editor and a 24/7 AI tutor. The Lua Academy course includes 4 lessons in total.

What will I learn in “table.concat and table.move”?

Efficiently join arrays and copy table slices with built-in functions. You practise Lua Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.

Do I need any experience to start Lua Academy?

No prior experience is required. Lua Academy on CoddyKit is structured for beginners through advanced learners, so you can start here or from the beginning and move at your own pace. This is lesson 2 of 4.

How long does the “table.concat and table.move” lesson take?

Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.

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All lessons in this course

table.sort with Comparators
table.concat and table.move
Deep Copy and Shallow Copy
Transforming Tables: map, filter, reduce

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