Regexps

Regular expressions, often shortened to regex or regexp, are sequences of characters that define a search pattern. They are a powerful tool for matching character combinations in strings. Regexps are widely used in text processing, data validation, searching, and parsing.

The fundamental building blocks of regexps include literal characters, which match themselves, and metacharacters, which have special meanings. Common metacharacters include periods that match any single character (except newline), asterisks that match the preceding element zero or more times, and plus signs that match the preceding element one or more times. Square brackets define character sets, allowing a match for any single character within the brackets. Parentheses are used for grouping and capturing parts of a match.

Different programming languages and tools implement regexps with slight variations in syntax and supported features. However, the core concepts remain largely consistent. Mastering regular expressions can significantly enhance a programmer's ability to manipulate and analyze text data efficiently. They provide a concise and flexible way to express complex search criteria that would be cumbersome to implement with traditional string comparison methods.