The Complete Regular Expressions Course with Exercises

Explore how regular expressions run across different engines in languages like C, JavaScript, Python, and Unix tools, and learn to test patterns with a regex tester or engine processor.

Explore offline engines to practice regular expressions, including chrome and firefox extensions, offline testers, and editors like notepad++, sublime text, and brackets.

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.

Explore how regex operators have special meaning and differ from mathematical symbols, and learn how regular expressions represent text for regex engines.

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.

Explore how character sets define matches in regular expressions, using brackets to select characters, and test with examples like varnish and cache to show set behavior and case sensitivity.

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.

Master restricting regular expressions by using the not symbol inside a character set to exclude specific characters, then match anything else, with practical examples and rules.

Escape metacharacters in regular expressions by prefixing with backslashes to treat forward slashes, dots, and backslashes literally; use \n and \t to match line breaks and tabs.

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.

Learn how regular expressions use backslash notations to match or negate characters, including backslash w for word characters, underscore, backslash s for space or tab, and backslash d for digits.

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 lazy expressions turn greedy quantifiers into non-greedy ones by placing a question mark after each quantifier, and observe how this affects matching quotes, wildcards, and digits.

Explore greedy and lazy testing in regular expressions, showing how the plus quantifier and the question mark alter matches through the grid approach and wildcard concepts.

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.

Master nested alternation in regular expressions by wrapping alternatives in groups to create multi-level choices, matching USA or China with blue while restricting to green for Canada or Russia.

Anchors mark positions rather than characters, using the caret symbol for the start and the dollar for the end of a string. Enable multiline mode to apply positions across lines.

Explore how anchors match the start and end of lines, using uppercase ranges, spaces, and punctuation to capture first or last sentences with escaped dots in regular expressions.

Explore alternative anchors in regular expressions, including beginning of string and end of line. Observe how multiline mode affects matches and how backslash anchors compare across engines.

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 in regular expressions to enable find-and-replace and reuse captured data. Demonstrate back references reusing captured groups with backslash numbers to match repeating patterns.

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.

Master a regex with capturing groups and back references to match 30 records—serials, social security numbers, names, and four-digit years—and swap first and last names via find and replace.

Learn how non capturing groups in regular expressions avoid data capture, speed up matching, and leave room for necessary captured groups while still supporting back references.

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.

Discover positive look ahead assertions in regular expressions, which have zero length and match something followed by another element without consuming it, as shown with Long Island and Ireland examples.

Explore how positive lookahead assertions extract the ending word of each sentence, excluding the dot, using word boundaries and lookahead in regular expressions.

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 look behind assertions, including positive and negative forms, with practical examples and a comparison to look ahead, while noting where they are supported and where they are not.

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.

Build an email regular expression with anchors, multiline mode, and a local and domain pattern, using character classes, escaping, and a negative lookahead to prevent consecutive dots.

Design and validate a regular expression to match urls with http, https, or ftp, including protocol, domain, and path, using grouping, alternation, escaping, and non-capturing techniques.

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.

Create regular expressions to validate dates by matching month, day, and year with optional leading zeros and dash or slash separators; restrict year to 2000–2049.

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.