Ruby Q & A


What is a regular expression in Ruby, and how to use it?

In Ruby, a regular expression, often referred to as a “regex” or “regexp,” is a powerful tool for pattern matching and text manipulation. It is a sequence of characters that defines a search pattern. Regular expressions are used to search for and manipulate text based on specific criteria, such as finding or replacing strings that match a particular pattern.

To use regular expressions in Ruby, you can create a regular expression object by enclosing the pattern within forward slashes (`/`). For example, the regular expression `/pattern/` will match the word “pattern” in a given text.

Here’s a basic overview of how to use regular expressions in Ruby:


  1. Matching: You can use the `=~` operator to check if a string matches a regular expression.

   text = "Hello, World!"

   if text =~ /World/

     puts "Found 'World' in the text."



   In this example, it will output “Found ‘World’ in the text.”


  1. Searching: You can use the `.match` method to search for a regular expression within a string and extract matched portions.

   text = "The price is $50."

   match_data = /($\d+)/.match(text)

   puts match_data[0]  # Outputs "$50"


   The parentheses in the regular expression create capture groups, allowing you to access matched portions individually.


  1. Replacing: The `.sub` and `.gsub` methods are used to replace substrings based on a regular expression pattern.

   text = "Apples are red. Bananas are yellow."

   modified_text = text.gsub(/red/, "green")


   `modified_text` will contain “Apples are green. Bananas are yellow.”

Regular expressions can be as simple or complex as your needs require. They offer a flexible way to perform tasks such as validation, searching, and text manipulation in Ruby. Learning regular expressions is a valuable skill for any developer who needs to work with text data.

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Experienced software professional with a strong focus on Ruby. Over 10 years in software development, including B2B SaaS platforms and geolocation-based apps.