The Ultimate Guide to Regular Expressions (Regex)

What is Regex?

Regular Expressions (Regex) are sequences of characters that define search patterns. They are used by programmers to validate inputs, search logs, and parse structured text files. While regex looks intimidating, it is built on simple rules.

Common Regex Metacharacters

• ^ - Matches the start of a line.
• $ - Matches the end of a line.
• \d - Matches any digit (0-9).
• [a-z] - Matches any lowercase letter.

Practical Pattern Examples

To validate a basic 5-digit postal code, you can use: ^\d{5}$. This tells the parser to search for exactly five digits from start to end without any trailing characters.