string

-- Single character
print(string.byte("A")) -- 65

-- Range of characters
print(string.byte("hello", 1, 3)) -- 104 101 108

-- Negative indices (counts from end)
print(string.byte("abc", -1)) -- 99 (the byte value of 'c')

-- Roundtrip with string.char
local a, b, c = string.byte("ABC", 1, 3)
print(string.char(a, b, c)) -- ABC

-- Basic usage
print(string.char(72, 101, 108, 108, 111)) -- Hello

-- Single character
print(string.char(65)) -- A

-- Construct from byte values (e.g. null byte)
local s = string.char(0)
print(#s) -- 1

-- Roundtrip with string.byte
local code = string.byte("Z")
print(string.char(code)) -- Z

-- Example 1: Basic usage
local s = "Hello, world!"
local pattern = "world"
local start_index, end_index = string.find(s, pattern)
print(start_index, end_index)  -- Output: 8 12

-- Example 2: Using init parameter
local s = "Hello, world! Hello, Roblox!"
local pattern = "Hello"
local start_index, end_index = string.find(s, pattern, 10)
print(start_index, end_index)  -- Output: 15 19

-- Example 3: Using plain parameter
local s = "Hello, world! (Hello)"
local pattern = "(Hello)"
local start_index, end_index = string.find(s, pattern, 1, true)
print(start_index, end_index)  -- Output: 14 20

-- Example 4: No Pattern found
local s = "Hello, world!"
local pattern = "Roblox"
local start_index, end_index = string.find(s, pattern)
print(start_index, end_index)  -- Output: nil

local str = "The magic word is %s"
print(string.format(str, "Roblox"))
-- The magic word is Roblox

local str = "The magic word is %q"
print(string.format(str, "Roblox"))
-- The magic word is "Roblox"

local str = "Skip to \na new line and \nanother new line!"
print(string.format(str, "%q"))
--[[ Output:
Skip to
a new line and
another new line!
]]

local str = "%-10d"
print(string.format(str, 300) .. "]")
-- 300       ]
-- There are 7 spaces between '300' and ']'

local str = "%+i versus %+i"
print(string.format(str, 300, -300)) -- +300 versus -300

local str = "There is a% i%% chance of rain in Seattle today."
print(string.format(str, 100))
-- There is a 100% chance of rain in Seattle today.

local str = "%012i"
print("Score: " .. string.format(str, 15000))
-- Output: Score: 000000015000
-- The output has 12 digits total, left-padded with zeros

-- Add decimal with precision of 2 for a currency output
local str = "$%.2f"
print(string.format(str, 300)) -- Output: $300.00

-- Return first 6 letters of a string
local str = "%.6s"
print(string.format(str, "Robloxian")) -- Output: Roblox

local str = "Once upon a time, there was a dragon named %s and it had %.8f horns."
print(string.format(str, "Pi", math.pi))
-- Output: Once upon a time, there was a dragon named Pi and it had 3.14159265 horns.

-- Iterate over all words in a sentence
for word in string.gmatch("Hello Roblox world", "%a+") do
    print(word)
end
-- Hello
-- Roblox
-- world

-- Extract key-value pairs using captures
local t = {}
for key, value in string.gmatch("name=Roblox, version=1.0", "(%w+)=(%w[%w.]*)") do
    t[key] = value
end
print(t.name, t.version) -- Roblox 1.0

-- Collect all digits
local digits = {}
for d in string.gmatch("abc123def456", "%d+") do
    table.insert(digits, d)
end
print(table.concat(digits, ", ")) -- 123, 456

-- Basic replacement
string.gsub("I love tacos!", "tacos", "Roblox") --> I love Roblox! 1
-- Replacement with a pattern
string.gsub("I like red!", "%w+", "word") --> word word word! 3
-- Replacement table
string.gsub("I play Roblox.", "%w+", {I="Je", play="joue à"}) --> "Je joue à Roblox." 3
-- Replacement function
string.gsub("I have 2 cats.", "%d+", function(n) return tonumber(n) * 12 end) --> "I have 24 cats." 1
-- Replace only twice
string.gsub("aaa", "a", "b", 2) --> "bba" 2
-- Replacement with capture groups (maximum of nine)
string.gsub("love2play Roblox", "(%w+)(%d+)(%w+)%s+(%w+)", "I %1 %2 %3 %4!") --> "I love 2 play Roblox!" 1

print(string.len("Hello")) -- 5
print(string.len(""))      -- 0

-- Embedded null bytes are counted
local s = "ab\0cd"
print(string.len(s)) -- 5

-- Equivalent to the # length operator
local str = "Roblox"
print(string.len(str) == #str) -- true

print(string.lower("HELLO")) -- hello
print(string.lower("Hello World!")) -- hello world!

-- Non-letter characters are unaffected
print(string.lower("Roblox 123!")) -- roblox 123!

-- Only ASCII letters are converted
print(string.lower("ABC abc")) -- abc abc

-- Extract matched substring
print(string.match("I have 42 cats", "%d+")) -- 42

-- Multiple captures
local year, month, day = string.match("2024-03-15", "(%d+)-(%d+)-(%d+)")
print(year, month, day) -- 2024 03 15

-- No match returns nil
print(string.match("hello", "%d+")) -- nil

-- Using init to skip ahead
print(string.match("foo123bar456", "%d+", 7)) -- 456

-- Anchored pattern
print(string.match("hello", "^%a+")) -- hello

print(string.rep("ab", 3))  -- ababab
print(string.rep("Go! ", 2)) -- Go! Go!

-- Zero or negative repeats return empty string
print(string.rep("x", 0))  -- (empty string)
print(string.rep("x", -1)) -- (empty string)

-- Useful for padding or separators
local separator = string.rep("-", 20)
print(separator) -- --------------------

print(string.reverse("hello"))  -- olleh
print(string.reverse("Roblox")) -- xolboR

-- Single character or empty string
print(string.reverse("a")) -- a
print(string.reverse(""))  -- (empty string)

-- Palindrome check
local function isPalindrome(s)
    local lower = string.lower(s)
    return lower == string.reverse(lower)
end
print(isPalindrome("racecar")) -- true
print(isPalindrome("hello"))   -- false

local input = "a,b,c"
local values = input:split(",")
print(values[1], values[2], values[3]) --> "a" "b" "c"

local result = string.split("", ",")
print(#result) --> 1
print(result[1]) --> ""

local result = string.split("foo,,bar", ",")
print(result[1], result[2], result[3]) --> "foo" "" "bar"

local result2 = string.split(",foo", ",")
print(result2[1], result2[2]) --> "" "foo"

local result3 = string.split("foo,", ",")
print(result3[1], result3[2]) --> "foo" ""

local result4 = string.split(",", ",")
print(result4[1], result4[2]) --> "" ""

local result5 = string.split(",,", ",")
print(result5[1], result5[2], result5[3]) --> "" "" ""

local result = string.split("   whitespace   ", ",")
print(result[1]) --> "   whitespace   "

local result2 = string.split("foo , bar", ",")
print(result2[1], result2[2]) --> "foo " " bar"

local result = string.split("\xFF", ",")
print(result[1]) --> "\xFF"

local result = string.split("\xFF,\xFE", ",")
print(result[1], result[2]) --> "\xFF" "\xFE"

local result = string.split("我很高兴，你呢？", "，")
print(result[1], result[2]) --> "我很高兴" "你呢？"

local result2 = string.split("hello•world", "•")
print(result2[1], result2[2]) --> "hello" "world"

local s = "Hello, world!"
print(string.sub(s, 1, 5))   -- Hello
print(string.sub(s, 8))      -- world!
print(string.sub(s, -6))     -- orld!
print(string.sub(s, -6, -2)) -- orld

-- Extract file extension
local filename = "script.lua"
local dot = string.find(filename, "%.")
print(string.sub(filename, dot + 1)) -- lua

-- Empty result when start > end
print(string.sub("abc", 3, 1)) -- (empty string)

print(string.upper("hello")) -- HELLO
print(string.upper("Hello World!")) -- HELLO WORLD!

-- Non-letter characters are unaffected
print(string.upper("roblox 123!")) -- ROBLOX 123!

-- Only ASCII letters are converted
print(string.upper("abc ABC")) -- ABC ABC