Question 1

What is a regular expression?

Accepted Answer

A regular expression (regex) is a sequence of characters that defines a search pattern. It is used to find, match, or replace text in strings. For example, the pattern \d+ matches one or more digits.

Question 2

What does \d mean in regex?

Accepted Answer

\d is a shorthand character class that matches any digit from 0 to 9. Other common shorthands include \w (word character: letters, digits, underscore), \s (whitespace), and \b (word boundary).

Question 3

What is the difference between greedy and lazy matching?

Accepted Answer

Greedy quantifiers (like * and +) match as many characters as possible. Lazy quantifiers (like *? and +?) match as few characters as possible. For example, <.+> matches the largest possible string between angle brackets, while <.+?> matches the smallest.

Question 4

How do I test a regular expression online?

Accepted Answer

Enter your regex pattern in the Pattern field and your test string in the text area above. Matches are highlighted live as you type, along with a count of total matches found.

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