kotlin regex

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To use regular expressions (regex) in Kotlin, you can make use of the Regex class, which represents a regular expression pattern. Here are the steps to use regex in Kotlin:

  1. Create a Regex pattern: Start by creating a Regex object that represents the pattern you want to match. You can do this by passing a string containing the regex pattern to the Regex constructor. For example, to create a regex pattern that matches a sequence of digits, you can write:

kotlin val pattern = Regex("\\d+")

In this example, the regex pattern is \\d+, which matches one or more digits.

  1. Match against a string: Once you have the regex pattern, you can use it to match against a string and find any matches. The find function of the Regex class can be used to find the first occurrence of the pattern in the string. For example:

kotlin val input = "12345" val matchResult = pattern.find(input)

In this example, the find function is called on the pattern regex object, passing the input string as the argument. The result is stored in the matchResult variable.

  1. Check for a match: The find function returns a MatchResult? object, which represents the result of the match. You can check if a match was found by using the != null comparison. For example:

kotlin if (matchResult != null) { // Match found val matchedValue = matchResult.value // Do something with the matched value } else { // No match found }

In this example, the != null comparison is used to check if a match was found. If a match is found, the value property of the MatchResult object can be accessed to get the matched value.

  1. Find all matches: If you want to find all occurrences of the pattern in the string, you can use the findAll function instead of find. The findAll function returns an Iterable<MatchResult> object that represents all the matches. For example:

kotlin val input = "12345" val matches = pattern.findAll(input) for (match in matches) { val matchedValue = match.value // Do something with each matched value }

In this example, the findAll function is called on the pattern regex object, passing the input string as the argument. The matches variable holds the Iterable<MatchResult> object, which can be iterated over to access each matched value.

These are the basic steps to use regex in Kotlin. You can modify the regex pattern according to your requirements and use the various functions provided by the Regex class to perform different operations on the matched values.