Match method and MatchData in Ruby

Introduction

The match method helps find patterns in text. It returns a MatchData object that holds details about the found pattern.

You want to check if a word or pattern exists in a sentence.

You need to extract parts of a string that match a pattern, like dates or emails.

You want to find where a pattern starts and ends in a string.

Syntax

Ruby

string.match(pattern)  # returns MatchData or nil

pattern is usually a regular expression (regex).

If the pattern is found, match returns a MatchData object; otherwise, it returns nil.

Examples

Finds the word 'world' in the string. Returns a MatchData object.

Ruby

"hello world".match(/world/)

Finds the first 3 digits in the string.

Ruby

"123-456".match(/\d{3}/)

Pattern not found, returns nil.

Ruby

"abc".match(/xyz/)

Sample Program

This program looks for a phone number pattern in the text. If found, it prints the number and where it starts.

Ruby

text = "My phone number is 555-1234."
result = text.match(/\d{3}-\d{4}/)
if result
  puts "Found phone number: #{result[0]}"
  puts "Starts at index: #{result.begin(0)}"
else
  puts "No phone number found."
end

Important Notes

You can access matched parts using result[0] for the whole match or result[n] for groups.

MatchData has useful methods like begin and end to find match positions.

Summary

The match method finds patterns in strings and returns a MatchData object if found.

MatchData holds details about the match, like the matched text and its position.

If no match is found, match returns nil.