Vital.sandbox - string.gsub

Syntax

local result, count = string.gsub(input, pattern, replacement, max_replacements = nil)

Parameters

Type	Name	Description
`string`	input	String to be converted
`string`	pattern	Lua pattern to find
`string`, `table` or `function`	replacement	Replacement string, table, or function
`int`	max_replacements	Maximum number of replacements to make

Returns

Type	Name	Description
`string`	result	Altered string with replacements
`int`	count	Number of substitutions that occurred

Examples

Simple text replacement

local result, count = string.gsub("hello world", "world", "Lua")

engine.print("info", result) --'hello Lua'
engine.print("info", count) --1

Replace all occurrences

local result = string.gsub("aaa", "a", "b")

engine.print("info", result) --'bbb'

Limit the number of replacements

local result, count = string.gsub("aaa", "a", "b", 2)

engine.print("info", result) --'bba'
engine.print("info", count) --2

Replace using a pattern

local result = string.gsub("hello world", "%a+", "word")

engine.print("info", result) --'word word'

Remove all spaces from a string

local result = string.gsub("h e l l o", " ", "")

engine.print("info", result) --'hello'

Replace all digits with a placeholder

local result = string.gsub("call 555-1234", "%d", "X")

engine.print("info", result) --'call XXX-XXXX'

Capture and reuse groups in replacement

local result = string.gsub("hello world", "(%a+)", "<%1>")

engine.print("info", result) --'<hello> <world>'

Swap two words using captures

local result = string.gsub("first second", "(%a+) (%a+)", "%2 %1")

engine.print("info", result) --'second first'

Use a function to transform matches

local result = string.gsub("I have 2 apples and 3 oranges", "%d+", function(n)
    return tonumber(n)*2
end)

engine.print("info", result) --'I have 4 apples and 6 oranges'

Use a table to map replacements

local replacements = {
    hello = "goodbye",
    world = "moon"
}
local result = string.gsub("hello world", "%a+", replacements)

engine.print("info", result) --'goodbye moon'

Capitalize the first letter of each word

local result = string.gsub("hello world from lua", "%a+", function(word)
    return string.upper(string.sub(word, 1, 1))..string.sub(word, 2)
end)

engine.print("info", result) --'Hello World From Lua'

Strip HTML tags from a string

local html = "<p>Hello <b>world</b></p>"
local result = string.gsub(html, "<[^>]+>", "")

engine.print("info", result) --'Hello world'

Escape special characters

local result = string.gsub("cost: $5.00", "%$", "USD ")

engine.print("info", result) --'cost: USD 5.00'

Convert snake_case to camelCase

local result = string.gsub("my_variable_name", "_(%a)", function(letter)
    return string.upper(letter)
end)

engine.print("info", result) --'myVariableName'

Return original string when pattern is not found

local result, count = string.gsub("hello", "xyz", "abc")

engine.print("info", result) --'hello'
engine.print("info", count) --0

string.gsub

Syntax

Parameters

Returns

Examples

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