Lua Academy · Lesson

if, elseif and else Statements

Write conditional branching logic with Lua's if/elseif/else syntax.

if, elseif and else Statements is a free Lua Academy lesson on CoddyKit — lesson 1 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Lua Academy learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.

Basic if Statement

The if statement evaluates a condition and executes its block when the condition is truthy. In Lua, only false and nil are falsy; everything else — including 0 and "" — is truthy. End the block with end.

local score = 85

if score >= 90 then
  print("A grade")
end

if score >= 60 then
  print("Passing")   -- prints
end

if 0 then
  print("0 is truthy!")  -- prints in Lua
end

if/elseif/else

Chain multiple conditions with elseif and provide a fallback with else. Lua evaluates conditions top to bottom and executes only the first matching branch. Unlike switch/case in other languages, Lua's elseif is a single keyword (not else if).

local score = 75

if score >= 90 then
  print("A")
elseif score >= 80 then
  print("B")
elseif score >= 70 then
  print("C")   -- prints
elseif score >= 60 then
  print("D")
else
  print("F")
end

Logical Operators in Conditions

Lua uses and, or, and not as logical operators. They short-circuit: and returns the first falsy value or the last value; or returns the first truthy value or the last value. This enables idiomatic default-value patterns.

local age = 25
local hasID = true

if age >= 18 and hasID then
  print("Entry allowed")
end

-- or for defaults
local name = nil
local display = name or "Guest"
print(display)   -- Guest

Ternary Idiom with and/or

Lua has no ternary operator, but the and/or pattern approximates it: condition and trueVal or falseVal. This works as long as trueVal is not false or nil. For safer ternary logic, use an inline if function.

local x = 10
local label = (x > 5) and "big" or "small"
print(label)   -- big

-- Safe ternary function
local function ternary(cond, t, f)
  if cond then return t else return f end
end
print(ternary(false, "yes", "no"))  -- no

Nested if Statements

You can nest if statements inside other branches. Each nested block requires its own end. Deep nesting often signals an opportunity to use early returns or guard clauses to flatten the logic.

local loggedIn = true
local isAdmin = false

if loggedIn then
  if isAdmin then
    print("Admin dashboard")
  else
    print("User dashboard")  -- prints
  end
else
  print("Login required")
end

Guard Clauses

A guard clause is an early return that handles invalid/edge cases at the top of a function, reducing nesting. This pattern keeps the "happy path" code unindented and easier to read.

local function processAge(age)
  if type(age) ~= "number" then
    return nil, "age must be a number"
  end
  if age < 0 then
    return nil, "age cannot be negative"
  end
  -- happy path
  return math.floor(age)
end

print(processAge(25.7))   -- 25
print(processAge(-1))     -- nil  age cannot be negative

Comparing Values

Lua comparison operators: == (equal), ~= (not equal), <, >, <=, >=. Note: ~= is Lua's "not equal" — not !=. String comparisons use lexicographic order. You cannot compare strings with numbers directly.

print(1 == 1)      -- true
print(1 ~= 2)      -- true
print("abc" < "abd")  -- true (lexicographic)
print("10" == 10)  -- false (different types)

-- Safe nil check
local val = nil
if val == nil then
  print("no value")
end

String Equality

Two strings are equal in Lua if and only if they have the same byte content and length. Lua interns strings, so equal strings often point to the same memory, making == a fast pointer comparison. Never compare strings with is or reference equality — == always compares by value.

local s1 = "hello"
local s2 = "hel" .. "lo"

print(s1 == s2)     -- true (same content)
print(s1 == "Hello") -- false (case sensitive)

-- Check for empty string
local name = ""
if name == "" or name == nil then
  print("name is empty or nil")
end

Table and Function Comparison

Tables and functions are compared by reference, not by content. Two different table literals with identical content are not equal unless they are the same object. Use metamethods like __eq to define custom equality for tables.

local t1 = {1, 2, 3}
local t2 = {1, 2, 3}
local t3 = t1

print(t1 == t2)   -- false (different objects)
print(t1 == t3)   -- true (same reference)

local f1 = function() end
local f2 = function() end
print(f1 == f2)   -- false

Idiomatic Patterns

Common Lua idioms with conditionals: use assert() to validate preconditions, use the and/or trick for short defaults, and avoid double-negatives (not not x) to convert any value to boolean.

-- assert pattern
local function sqrt(n)
  assert(n >= 0, "sqrt of negative")
  return math.sqrt(n)
end

-- Convert to boolean
local val = 42
local boolVal = not not val
print(boolVal)   -- true

-- Default parameter
local function greet(name)
  name = name or "World"
  print("Hello, " .. name)
end
greet()          -- Hello, World

Quick Check

Which values are falsy in Lua?

Recap: Conditionals

Summary:

if ... elseif ... else ... end — the full branching form
Only nil and false are falsy
and/or short-circuit and return operand values
~= is "not equal" in Lua (not !=)
Tables/functions compare by reference, strings by value
Use guard clauses to reduce nesting

Frequently asked questions

Is the “if, elseif and else Statements” lesson free?

Yes — the full text of “if, elseif and else Statements” is free to read here on the web, and the Lua Academy course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Lua Academy course, upgrade to CoddyKit PRO.

What will I learn in “if, elseif and else Statements”?

Write conditional branching logic with Lua's if/elseif/else syntax. 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; this is — lesson 1 of 4, so you can start here or from the beginning and move at your own pace.

How long does the “if, elseif and else Statements” 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.

Can I write and run code in this Lua Academy lesson?

Yes. Every Lua Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.

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