Welcome to the Regex Tutorial! Regular expressions (regex) are a powerful tool used for pattern matching in strings. They are widely used in programming, data processing, and text analysis.

What is a Regex?

A regular expression is a sequence of characters that defines a search pattern. It can be used to search for specific patterns within strings, validate input, or manipulate text.

Basic Syntax

  • . matches any character except a newline.
  • * matches zero or more of the preceding element.
  • + matches one or more of the preceding element.
  • ? matches zero or one of the preceding element.
  • [] defines a character set, matching any single character within the brackets.
  • ^ asserts the position at the start of a line.
  • $ asserts the position at the end of a line.

Examples

Here are some examples of regex patterns and their matches:

  • a.*b matches any string that starts with 'a' and ends with 'b'.
  • [a-z] matches any lowercase letter.
  • ^Hello matches any string that starts with 'Hello'.
  • world$ matches any string that ends with 'world'.

Resources

For more information on regex, you can refer to the following resources:

Regex Example