[Setup] Lua Runtime Environment

# -----------------------------------------------
# Install on Ubuntu / Debian
# -----------------------------------------------
sudo apt update
sudo apt install lua5.4        # Install Lua 5.4

# -----------------------------------------------
# Install on macOS (Homebrew)
# -----------------------------------------------
brew install lua               # Install the latest Lua

# -----------------------------------------------
# Install on Windows (Scoop)
# -----------------------------------------------
scoop install lua              # Install via Scoop package manager

# -----------------------------------------------
# Check version
# -----------------------------------------------
lua -v                         # Show the installed Lua version

# -----------------------------------------------
# Start the interactive REPL
# -----------------------------------------------
lua                            # Running without arguments starts the REPL
# Lua 5.4.6  Copyright (C) 1994-2023 Lua.org, PUC-Rio
# The > prompt accepts Lua expressions
# To exit the REPL, use os.exit() or Ctrl+D

# -----------------------------------------------
# Run a script file
# -----------------------------------------------
lua hello.lua                  # Run the specified script file
lua -e "print('hello')"        # Run a string directly with the -e option

kof_setup.lua

-- kof_setup.lua
-- Uses KOF (The King of Fighters) characters to demonstrate
-- variables, tables, functions, and loops.

-- -----------------------------------------------
-- Variables and print
-- -----------------------------------------------

local title = "THE KING OF FIGHTERS"
local version = _VERSION  -- _VERSION is a global holding the version string (e.g., "Lua 5.4")

print("=== " .. title .. " ===")
print("Runtime: " .. version)
print("")

-- -----------------------------------------------
-- Tables (Lua's combined array and dictionary)
-- -----------------------------------------------

local fighters = {
    { name = "Terry Bogard",  team = "Fatal Fury Team", power = 95 },
    { name = "Andy Bogard",   team = "Fatal Fury Team", power = 90 },
    { name = "Mai Shiranui",  team = "Fatal Fury Team", power = 88 },
    { name = "Joe Higashi",   team = "Fatal Fury Team", power = 85 },
    { name = "Ralf Jones",    team = "Ikari Team",      power = 93 },
}

-- -----------------------------------------------
-- Function definition
-- -----------------------------------------------

local function evaluate(power)
    if power >= 95 then
        return "S Rank"
    elseif power >= 90 then
        return "A Rank"
    else
        return "B Rank"
    end
end

-- -----------------------------------------------
-- Iterating a table with a for loop
-- -----------------------------------------------

print("--- Fighter List ---")
-- ipairs iterates in order with an index
for i, fighter in ipairs(fighters) do
    local rank = evaluate(fighter.power)
    -- string.format produces formatted output
    print(string.format("  %d. %s (%s) Power: %d [%s]",
        i, fighter.name, fighter.team, fighter.power, rank))
end
print("")

-- -----------------------------------------------
-- while loop example
-- -----------------------------------------------

print("--- Countdown ---")
local count = 3
while count > 0 do
    print("  " .. count .. "...")
    count = count - 1  -- Lua has no -= operator; use assignment instead
end
print("  FIGHT!")
print("")

-- -----------------------------------------------
-- String operations
-- -----------------------------------------------

local hero = "Terry Bogard"
print("--- String Operations ---")
print("  Name: " .. hero)
print("  Length (bytes): " .. #hero)             -- # operator returns byte length
print("  Uppercase: " .. string.upper("terry"))  -- Only ASCII characters are uppercased
print("")

-- -----------------------------------------------
-- Closing message
-- -----------------------------------------------

print("Setup complete. Lua is running correctly.")

lua kof_setup.lua
=== THE KING OF FIGHTERS ===
Runtime: Lua 5.4

--- Fighter List ---
  1. Terry Bogard (Fatal Fury Team) Power: 95 [S Rank]
  2. Andy Bogard (Fatal Fury Team) Power: 90 [A Rank]
  3. Mai Shiranui (Fatal Fury Team) Power: 88 [B Rank]
  4. Joe Higashi (Fatal Fury Team) Power: 85 [B Rank]
  5. Ralf Jones (Ikari Team) Power: 93 [A Rank]

--- Countdown ---
  3...
  2...
  1...
  FIGHT!

--- String Operations ---
  Name: Terry Bogard
  Length (bytes): 12
  Uppercase: TERRY

Setup complete. Lua is running correctly.

'Lua' is a lightweight scripting language implemented in C. It can be installed on any OS using the standard package manager (apt, Homebrew, or Scoop). Use lua -v to check the version, run lua alone to start the interactive REPL and evaluate expressions on the spot, and run lua filename.lua to execute a script file. Because Lua variables are global by default, attaching local to variable declarations is the standard practice for limiting scope. The 'table' — which unifies arrays and dictionaries — is the central data structure in Lua. See also Table Basics.