What is Regular Expressions (Regex)?

**Regular Expressions (Regex)** are powerful sequences of characters that define search patterns, primarily used for string pattern matching and manipulation. They are widely utilized in programming, data validation, text processing, and more to perform complex searches, replacements, and data extraction tasks efficiently.

Examples of Regex Usage:

• Example 1: Matching Capitalized Words
  • Regex Pattern: `/\b[A-Z][a-z]+\b/`
  • Input Text: "Hello world, this is Regex Tester."
  • Expected Result: Matches "Hello" and "Regex"
• Example 2: Validating Social Security Numbers (SSN)
  • Regex Pattern: `/\b\d{3}-\d{2}-\d{4}\b/`
  • Input Text: "My SSN is 123-45-6789."
  • Expected Result: Matches "123-45-6789"
• Example 3: Extracting Gmail Addresses
  • Regex Pattern: `/\b\w+@gmail\.com\b/`
  • Input Text: "Contact us at support@gmail.com or sales@yahoo.com."
  • Expected Result: Matches "support@gmail.com"

How to Use the Regex Tester Online Tool:

1. Enter Your Text: Paste or type the text you want to test against your regex pattern into the "Input Text" textarea.
2. Enter Regex Pattern: Input your regular expression into the "Regex Pattern" field. Ensure that your regex is correctly formatted to avoid errors.
3. Specify Replacement Text (Optional): If you want to perform a replace operation, enter the replacement text in the "Replacement Text" field. This will replace the matched patterns with the specified replacement.
4. Select Regex Options:
   • Case Insensitive (i): Makes the regex pattern case-insensitive, allowing it to match letters regardless of their case.
   • Global Match (g): Finds all matches in the text rather than stopping after the first match.
   • Multiline Mode (m): Treats the input as multiple lines, affecting how `^` and `$` anchors behave.
   • Dotall Mode (s): Allows the dot `.` to match newline characters, enabling matches across multiple lines.
5. Additional Options:
   • Highlight Matches in Input Text: Visually highlights all matches within the input text for easy identification.
   • Show Match Positions: Displays the starting and ending positions of each match within the text.
   • Download Results as Text File: Enables downloading the match and replace results as a `.txt` file for offline use.
   • Copy Results to Clipboard: Allows copying the results directly to your clipboard with a single click.
6. Test Regex: Click the "Test Regex" button to execute the regex against your input text based on the selected options.
7. Review Results:
   • Modified Text: If a replacement operation was performed, the modified text will appear in the "Modified Text" textarea.
   • Matches Found: A list of all matches will be displayed, along with their positions if the option was selected.
   • Highlighted Input Text: If enabled, matches within the input text will be highlighted for easy visualization.
   • Download and Copy Options: Utilize the provided buttons to download or copy the results as needed.