Regex Tutorial - Getting Started

📅 2026-06-12 | 📂 Regex

Introduction

Regular expressions (regex) are patterns used to match character combinations in strings. They are a powerful tool for text processing, validation, and data extraction.

Basic Syntax

# Literal matching
/Hello/       matches "Hello"

# Special characters
.             Any single character
d            Any digit (0-9)
w            Word character (a-z, A-Z, 0-9, _)
s            Whitespace (space, tab, newline)

# Examples
/HellosWorld/    matches "Hello World"
/d{3}/           matches "123"
/w+@w+.w+/    matches "user@example.com"

Practical Examples

# Match email addresses
/[w.]+@+.+/

# Match phone numbers
/d{3}-d{3}-d{4}/

# Match URLs
/https?://[w.-]+/

# In JavaScript
const regex = /d+/g;
const result = "I have 5 cats and 3 dogs".match(regex);
// ["5", "3"]

Using Regex in Code

# Python
import re
pattern = r'd+'
result = re.findall(pattern, "12 apples and 34 oranges")
# ['12', '34']

# JavaScript
const pattern = /d+/g;
const result = "12 apples".match(pattern);

Summary

Regex uses patterns to find and manipulate text. Start with basic metacharacters like ., d, w, and s, then build complex patterns for real-world tasks.

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