Italian CAP (Codice di Avviamento Postale) Regex for Python

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching italian cap (codice di avviamento postale), ported and verified for Python. A rigorously tested regex reduces debugging time and protects your application from edge-case failures. The snippet below is ready to drop into your Python project — whether you're validating in a Django view, a FastAPI endpoint, or a standalone data processing script.

Python Implementation

# Italian CAP (Codice di Avviamento Postale)
# ReDoS-safe | RegexVault — Localization > Postal Codes

import re

italian_cap_codice_di_avviamento_postale_pattern = re.compile(r'^(?!00000)[0-9]{5}$')

def validate_italian_cap_codice_di_avviamento_postale(value: str) -> bool:
    return bool(italian_cap_codice_di_avviamento_postale_pattern.fullmatch(value))

# Example
print(validate_italian_cap_codice_di_avviamento_postale("00100"))  # True

Test Cases

When to use this pattern

This pattern is drawn from the Localization > Postal Codes category and carries a ReDoS-safe certification. That matters for Python developers because particularly important in Python web servers where CPU-bound regex operations can stall concurrent request handling. RegexVault audits patterns against known backtracking attack vectors, ensuring you have the necessary context before using this regex in a high-stakes production environment.

Common Pitfalls

Technical Notes

Italian CAP ranges: 00xxx (Rome/Lazio area) to 98xxx. 00100 is Rome. Ranges are broadly north-to-south (20xxx Milan, 80xxx Naples). San Marino uses 4780x, Vatican City uses 00120.