Regex

Set 1: Basics – Literal Matches and Simple Character Classes
Focus: Matching exact strings and basic patterns
Match the word "India"

Regex: India

Explanation: Matches the exact word "India" anywhere in the text.

Match either "Delhi" or "Mumbai"

Regex: Delhi|Mumbai

Explanation: Matches either of the two city names.

Match any single digit (e.g., part of a pincode)

Regex: [0-9]

Explanation: Matches any single digit from 0 to 9.

Match all vowels (useful for analyzing names)

Regex: [aeiouAEIOU]

Explanation: Matches any vowel (both lowercase and uppercase).

Match the word "Namaste" exactly at the start of a sentence

Regex: ^Namaste

Explanation: ^ anchors the pattern to the beginning of a line.

Set 2: Quantifiers and Common Formats
Focus: Using +, *, {n}, ?
Match a sequence of 5 digits (Indian pincode)

Regex: \b\d{6}\b

Explanation: Matches exactly 6-digit numbers; \b ensures word boundary.

Match a word like “Ram”, “Rama”, “Ramaa”, etc.

Regex: Rama*

Explanation: Matches "Ram", "Rama", "Ramaa", etc. (a* = 0 or more a's)

Match names starting with 'A' followed by any 2 letters

Regex: A[a-zA-Z]{2}

Explanation: Matches strings like “Ami”, “Aru”, etc.

Match a string that ends with “ji” (e.g., Gandhi ji)

Regex: ji$

Explanation: $ anchors to the end of the string.

Match any word containing at least one vowel

Regex: \b\w*[aeiouAEIOU]\w*\b

Explanation: \w* matches any word with at least one vowel.

Would you like me to continue with the next 5 examples? The next set will start exploring groups, more complex alternation, and Indian-specific formats like phone numbers and vehicle registration numbers.

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Next 5
ChatGPT said:
Great! Here's the next batch.

Set 3: Grouping, Alternation, and Indian-Specific Formats
Focus: Using parentheses (), grouping with |, and applying to real-life Indian formats
Match either “Kolkata” or “Chennai” or “Bengaluru”

Regex: (Kolkata|Chennai|Bengaluru)

Explanation: Grouping with | lets you match any one of these cities.

Match Indian mobile numbers starting with 7, 8, or 9

Regex: [789]\d{9}

Explanation: Matches a 10-digit mobile number starting with 7, 8, or 9.

Match vehicle registration numbers like KA01AB1234

Regex: [A-Z]{2}\d{2}[A-Z]{2}\d{4}

Explanation: Matches Indian vehicle plates (e.g., KA01AB1234, DL09CD6789).

Match PAN card format (e.g., ABCDE1234F)

Regex: [A-Z]{5}[0-9]{4}[A-Z]

Explanation: Matches PAN structure – 5 uppercase letters, 4 digits, 1 uppercase letter.

Match Aadhaar numbers (12-digit format, optional spaces)

Regex: \d{4} ?\d{4} ?\d{4}

Explanation: Matches Aadhaar numbers with or without spaces (e.g., 123456789012 or 1234 5678 9012).

Would you like the next 5 examples to focus on email validation, name patterns, and Indian website formats? Or shall we go deeper into advanced regex concepts like lookaheads, backreferences, etc.?

You said:
Next 5
ChatGPT said:
Perfect! Here's the next set.

Set 4: Indian Names, Emails, and Web Patterns
Focus: Character classes, optional elements, and realistic Indian data
Match typical Indian names starting with capital (e.g., “Amit”, “Suresh”, “Priya”)

Regex: [A-Z][a-z]{2,}

Explanation: Matches a capital letter followed by at least two lowercase letters – good for basic name detection.

Match common Indian email addresses (e.g., [email protected])

Regex: [a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.(com|in)

Explanation: Matches Gmail, Yahoo, etc. ending in .com or .in – commonly used domains in India.

Match Indian website URLs like www.irctc.co.in

Regex: www\.[a-zA-Z0-9\-]+\.(com|in|co\.in)

Explanation: Matches websites ending in common Indian domains like .in and .co.in.

Match names with optional title (e.g., Mr. Sharma, Mrs. Rani)

Regex: (Mr|Mrs|Ms)\.?\s[A-Z][a-z]+

Explanation: Matches optional period after title, then a capitalized surname.

Match hashtags used in Indian context (e.g., #India, #IPL2025)

Regex: #\w+

Explanation: Matches hashtags (words beginning with # and followed by letters/digits).

Let me know if you'd like to continue to the next 5. We can start getting into lookaheads, backreferences, or custom validations like matching date formats (e.g., 13/04/2025), or GSTIN numbers.

You said:
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ChatGPT said:
Awesome, let’s keep it rolling!

Set 5: Dates, Times, and Advanced Indian Format Validation
Focus: Date/time patterns, character escapes, and real-world validation
Match Indian date format DD/MM/YYYY (e.g., 13/04/2025)

Regex: \b\d{2}/\d{2}/\d{4}\b

Explanation: Matches dates in day/month/year format with slashes.

Match 24-hour time format (e.g., 14:35, 09:00)

Regex: \b([01]\d|2[0-3]):[0-5]\d\b

Explanation: Validates 00:00 to 23:59 format.

Match Indian currency values (e.g., ?500, ?12,34,567.89)

Regex: ?[0-9,]+(\.\d{2})?

Explanation: Matches ? followed by Indian-style numerals with optional paise.

Match Indian GSTIN (Goods and Services Tax Identification Number)

Regex: \d{2}[A-Z]{5}\d{4}[A-Z]{1}[A-Z\d]{1}[Z]{1}[A-Z\d]{1}

Explanation: Matches the 15-character alphanumeric GSTIN format.

Match Indian STD codes (e.g., 011, 022, 080)

Regex: 0\d{2,3}

Explanation: Matches STD codes starting with 0 and 2–3 digits.

We're halfway through! ??
Ready for the next 5? Shall we continue with lookaheads, validations, or regional language elements (like Hindi text in Unicode)?

You said:
Next
ChatGPT said:
Love the momentum! Here's the next batch.

Set 6: Lookaheads, Word Boundaries, and Unicode (Indian Language Basics)
Focus: Lookaheads, word boundaries, and basic Hindi character matching
Match a word that starts with "Bharat" but doesn’t end with "Mata"

Regex: \bBharat(?!.*Mata)\b

Explanation: Negative lookahead ensures "Mata" doesn’t appear after "Bharat".

Match a sentence that contains "India" only if it's followed by "is great"

Regex: India(?= is great)

Explanation: Positive lookahead ensures "India" is only matched when followed by "is great".

Match exact word "chai" as a standalone word

Regex: \bchai\b

Explanation: Word boundaries (\b) ensure it doesn’t match "chaibreak" or "masalachai".

Match Hindi characters (Devanagari script, e.g., ??????)

Regex: [\u0900-\u097F]+

Explanation: Matches one or more characters in the Devanagari Unicode range.

Match sentences ending with "hai" (common in spoken Hindi)

Regex: \b\w+\s+hai\.?$

Explanation: Matches lines ending with "hai" optionally followed by a period.