Searching and replacing text

Lua:
Searching and replacing text

How to:

Lua’s string.gsub function is your go-to for search and replace. It works like this:

local text = "The quick brown fox jumps over the lazy dog."
local searchText = "lazy"
local replaceWith = "energetic"

local result = string.gsub(text, searchText, replaceWith)

print(result)

Output:

The quick brown fox jumps over the energetic dog.

To replace ALL occurrences, gsub does it by default:

local text = "Apples are sweet. Apples are juicy."
local result = string.gsub(text, "Apples", "Oranges")

print(result)

Output:

Oranges are sweet. Oranges are juicy.

Deep Dive

Searching and replacing text is not unique to Lua; it’s a common feature in programming languages. Lua’s string.gsub goes back to its string manipulation roots, offering a straightforward approach to handle patterns and replacements.

Historically, gsub (global substitution) is influenced by Unix’s sed command and Perl’s powerful pattern matching capabilities. Lua’s patterns, albeit simpler than regular expressions found in other languages, can still handle complex matches with a little creativity.

Alternatives to string.gsub include manually iterating through strings and constructing replacements—a more error-prone method. For heavy text processing, dedicated parsing libraries can be used.

Implementation-wise, gsub can take a function as a replacement argument allowing programmatic control over the substitution.

local result = string.gsub(text, "(%a+)", function(word)
  return #word > 4 and word:upper() or word
end)

This snippet will uppercase words longer than four characters.

Lua:Searching and replacing text

How to:

Deep Dive

See Also

Lua:
Searching and replacing text