string

Returns the internal numerical codes of the characters s[i], s[i+1], ..., s[j]. The default value for i is 1; the default value for j is i. These indices are corrected following the same rules of function string.sub().

Receives zero or more integers and returns a string with length equal to the number of arguments, in which each character has the internal numerical code equal to its corresponding argument.

Searches for the first occurrence of a pattern in a string and returns the start and end indices of the match. If no match is found, it returns nil. You can specify where to start the search using the optional init parameter which defaults to 1 and can be negative. An optional plain parameter turns off pattern matching, so the function performs a plain substring search; note that if you use plain, you must also provide init.

-- 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

Returns a formatted version of its variable number of arguments following the description given in its first argument, which must be a string.

You can convert variables into user-friendly strings of text using the string.format() function. The function requires the following format:

%[flags][width].[precision][specifier].

Specifiers

The most important part of string formatting is the specifiers.

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!
]]

Flags

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.

Width

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

Precision

The default precision is 1. If you give a period without a value, the default is 0.

-- 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.

Returns an iterator function that returns the next captures from pattern over the string s each time it's called.

Short for global substitution. Returns a copy of s in which all (or the first n, if given) occurrences of the pattern are substituted (replaced) with the given replacement. The second value returned is the total number of substitutions made.

The replacement can be one of several types, each used differently to determine the actual string:

• string: The pattern is replaced with the string directly
• table: The string that matched the pattern is looked up in the table as a key, and the value (string) is what replaces it, if it exists.
• function: Called with the string that matched the pattern, should return the string to replace the matched pattern.

An optional final argument can be provided which specifies the maximum number of substitutions to make (for example, stop after 2 replacements)

Various Examples

-- 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

Returns the length of a string.

Returns a copy of a string with all uppercase letters changed to lowercase.

Looks for the first match of pattern in the string s. If a match is found, it is returned; otherwise, it returns nil. A third, optional numerical argument, init, specifies where to start the search; its default value is 1 and can be negative.

Returns a binary string containing the provided arguments. The first argument, format, determines the way the remaining arguments are packed; see here for options.

Returns the size in bytes of any string packed with a given description. The sole argument, format, determines the way the remaining arguments are packed, but you cannot use s and z because they have variable lengths. See here for options.

Returns a string that is the concatenation of n copies of the string s.

Returns a string that is the string s reversed.

Splits a string into parts based on the defined separator character(s), returning a table of ordered results.

If an empty "slice" is located, that part will be returned as an empty string. For instance string.split("abc||def", "|") will return a table with three strings: "abc", "", and "def".

local values = input:split(",")
print(values[1], values[2], values[3])

Also note that whitespace from the original string will be preserved, for example string.split("abc _ def", "_") will honor the whitespace on both sides of the _ separator. By default, the separator character is , but you can specify an alternative character or series of characters.

Corner Cases

Empty String

"" --> ""

Empty Slices

"foo,,bar" --> "foo", "", "bar"
",foo" --> "", "foo"
"foo," --> "foo", ""
"," --> "", ""
",," --> "", "", ""

Whitespace Preserved

"   whitespace   " --> "   whitespace   "
"foo , bar" --> "foo ", " bar"

Invalid UTF-8

"\xFF" --> "\xFF"
"\xFD,\xFE" --> "\xFD", "\xFE"

Unicode

"，" --> U+FF0C FULLWIDTH COMMA
"我很高兴，你呢？" --> "我很高兴", "你呢？"
"•" --> U+2022 BULLET
"hello•world" --> "hello", "world"

Returns the substring of s that starts at i and continues until and including j. i and j can be negative. i defaults to 1 and j defaults to -1.

Extracts the values packed in the provided binary string based on the first argument, format, which should match the one originally used to pack() the string; see here for options. The optional third parameter determines the byte at which the reading starts.

Returns a copy of a string with all lowercase letters changed to uppercase.