MUDLET STRING FUNCTIONS HOW TO
MUDLET STRING FUNCTIONS MANUAL

What if you want to get certain pieces out of a string of text? This can be done by wrapping parts of a pattern in ( ), and the contents of each of these captures will be returned from string.match. The solution is to prepend them with a % character:

MUDLET STRING FUNCTIONS HOW TO

They're not just for use with -, you can just prepend the pattern with ^ to make it match at the start, append $ to make it match at the end, and wrap it in both (like the example above) to make it match the whole string.įinally, you might be thinking how to match all these special characters literally. Here we also introduced ^ and $, which match the start and end of the string. > = string.match( 'abc', '^.-b') - the ^ matches the start of the string > = string.match( 'abc', 'a.-$') - the $ matches the end of the string When using -, you need to remember to 'anchor' it from both sides, otherwise it will match nothing (since it tries to match as little as possible): > = string.match( 'one |two| three |four| five', '|*|') - another solution can be to not let the contents match the delimiter > = string.match( 'one || three', '|.+|')Ī common mistake with + and * is not realizing that they match as much as possible, which may not be the desired result. > = string.match( 'this is some text with a number 12345 in it', '%d+') Note how it's used with a class, so it can match a sequence of different characters: > = string.match( 'example', 'examples?') > = string.match( 'examples', 'examples?') We'll start with ?, since it's the simplest: ? Make the previous character (or class) optional.- Match the previous character (or class) zero or more times, as few times as possible.+ Match the previous character (or class) one or more times, as many times as possible.* Match the previous character (or class) zero or more times, as many times as possible.To solve this, patterns support these four repetition operators: > = string.match( '123', '') - you can specify a range of characters using -Įven with character classes this is still very limiting, because we can only match strings with a fixed length. If the first character inside the brackets is ^, then it will match a character not in the group. You can also create your own classes by wrapping a group of characters in square brackets.

MUDLET STRING FUNCTIONS MANUAL

See the patterns manual (linked at the top of the tutorial) for a list of all pre-defined classes. Making the letter after the % uppercase inverts the class, so %D will match all non-digit characters. > = string.match( 'text with an Uppercase letter', '%u') - %u matches an uppercase letter > = string.match( 'foo 123 bar', '%d%d%d') - %d matches a digit Patterns have a few pre-defined classes, use them as '%x', where 'x' is the letter identifying the class: It returns the matched text, or nil if the pattern is not found: (actually, find also returns the matched text, but it first returns the indexes match only returns the text) We can now use these indices to get the matched text, but there's a better way: the string.match function. is a character class that matches any character: A character class is a pattern that matches one of a set of characters.

> = string.find( 'banana', 'lua') - 'lua' will not be found nilīut literally matching text isn't that useful, so patterns have the concept of character classes. > = string.find( 'banana', 'an') - find 1st occurance of 'an' (letters are matched literally) If you're used to other languages that have regular expressions to match text, remember that Lua's pattern matching is not the same: it's more limited, and has different syntax.Īfter reading this tutorial, it's very strongly recommended to read the manual on patterns, so you know everything it offers.įirst we will use the string.find function, which finds the first occurrence of a pattern in a string and returns start and end indices of the first and last characters that matched the text: Lua patterns can match sequences of characters, where each character can be optional, or repeat multiple times. Lua-users wiki: Patterns Tutorial Patterns Tutorial

Mudlet string functions