string.match()

While string.find() tells you where a pattern appears in a string, sometimes you need to extract the actual text that matched. This is where string.match() comes in, and it becomes even more powerful when combined with captures.

Captures allow you to mark specific parts of a pattern that you want to extract. You create a capture by wrapping part of your pattern in parentheses (). When string.match() finds a match, it returns the captured text instead of just the position.

Here's a simple example extracting a number from a string:

local text = "Player score: 100"
local number = string.match(text, "%d+")
print(number)  -- Output: 100

The pattern %d+ means "one or more digits." The + is a modifier that matches one or more of the preceding character class, allowing you to capture multi-digit numbers.

You can use captures to extract specific parts of a more complex pattern:

local message = "User: Alice sent a message"
local username = string.match(message, "User: (%a+)")
print(username)  -- Output: Alice

Here, the parentheses around %a+ tell Lua to capture the sequence of letters that comes after "User: ". The rest of the pattern helps locate the right position, but only the captured part is returned.

If your pattern has multiple captures, string.match() returns all of them as separate values, which you can assign to multiple variables at once.