Programming Ruby 3.3

What Regular Expressions Let You Do

A regular expression is a pattern that can be matched against a string. It can be a simple pattern, such as the string must contain the sequence of letters “cat,” or the pattern can be complex, such as the string must start with a protocol identifier, followed by two literal forward slashes, followed by…, and so on. This is cool in theory. But what makes regular expressions so powerful is what you can do with them in practice:

• You can test a string to see whether it matches a pattern.
• You can extract from a string the sections that match all or part of a pattern.
• You can change the string, replacing the parts that match a pattern.

Ruby provides built-in support that makes pattern matching, extraction, and substitution ...