The Complete Regular Expressions Course with Exercises

Practice writing and testing regular expressions using engines and testers, switching between JavaScript and Python flavors with tools like regex one on one dot com and logic spell dot com.

Master the basic syntax of regular expressions by enclosing patterns in forward slashes (avoid slashes inside patterns) and testing them in a regex tester with test strings and matches.

Learn how literal characters in regular expressions match exact text, using forward slashes and color examples to illustrate matches.

Discover regex modes like global (G), case-insensitive, standard, and multiline, and see how they affect matches through hands-on testing on a regex tester.

Learn how wild card metacharacters work in regular expressions, where a dot matches any character except newline, and how global mode, single-line mode, and escaping dots with backslashes affect matching.

Master character ranges in regular expressions to match lowercase and uppercase letters and digits. Use dash‑separated ranges inside a character class, mix ranges, and limit digits to 0–9.

Learn which characters you must escape inside a character set in regular expressions. Escape dash, forward slash, asterisk, and the closing bracket to ensure correct matching across engines.

Discover quantified repetitions in regular expressions, using optional with a question mark, zero or more with static, and one or more with plus, through practical examples.

Define exact and range repetition in regular expressions using curly braces, set minimum and maximum occurrences, and apply them to digits, SSN formats, and phone patterns.

Explore how greedy quantifiers in regular expressions drive backtracking as the engine matches as much as possible, then backtracks to fit the remaining pattern and complete matches.

Learn how to create and use groups in regular expressions to repeat patterns, enforce character ranges, and improve readability, then apply groups for find-and-replace operations.

Apply alternation in regular expressions using the pipe symbol to make choices, group alternatives with parentheses, and test matches like boy or girl, or Pakistan, India, Australia.

Explore how word boundaries work in regular expressions, using the word boundary anchor with word characters and nonword transitions to match whole words. Learn zero-length boundaries and practical examples.

Explore capturing groups and back-references to detect repeating words, use word boundaries and global mode, then apply back-references to match opening and closing HTML tags and handle tag boundaries.

Explore look around assertions, including look ahead and look behind, as zero-width checks that verify a match without consuming characters and enable concise regex design.

Learn to craft regex with positive lookahead assertions to validate phone numbers, constraining digits and dashes from start to end in multiline mode, and test multiple lookahead combinations.

Discover negative lookahead assertions and their contrast with positive lookahead, using zero-width checks to match patterns not followed by a sequence, illustrated with long drive, long beach, not long island.

Explore how Unicode extends bits into a variable-length encoding supporting Arabic, Chinese, and Hindi. Learn regex Unicode notation using u+ four-hex digits and backslash forms.

Discover building regular expressions for names that start with a capital letter, allow spaces and commas, enforce length, and use negative lookahead to prevent consecutive spaces.

Design and test a regular expression for IP addresses, restricting each octet to 0–255, validating four dot-separated numbers, and using non-capturing groups to match valid patterns.

Learn to build regular expressions for time in both 12-hour and 24-hour formats, matching hours (1–12 or 0–23), minutes and seconds (0–59), with optional am/pm, separators, and optional gmt annotations.

Explore regular expressions for postal codes across countries, including Pakistan's five digits, India's six digits, Canada's alphanumeric pattern with a space, and the USA or UK formats.

Develop a regex to match Visa, MasterCard, Discover, China UnionPay, and American Express numbers, supporting sixteen or fifteen digits with spaces or dashes, and enforce format with back references.

Create a password regex that enforces eight to fifteen characters and requires at least one digit, one lowercase, one uppercase, and one symbol, using start-to-end anchors and lookahead assertions.

Practice every exercise to master regular expressions and see real-world PSP programming applications; discover related courses and discounts for expanding your skills.