Portuguese Código Postal (CP4-3) Regex for Python

What this pattern does

This page provides a lightweight, single-purpose regular expression for matching portuguese código postal (cp4-3), 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

# Portuguese Código Postal (CP4-3)
# ReDoS-safe | RegexVault — Localization > Postal Codes

import re

portuguese_cdigo_postal_cp43_pattern = re.compile(r'^([1-9][0-9]{3})-([0-9]{3})$')

def validate_portuguese_cdigo_postal_cp43(value: str) -> bool:
    return bool(portuguese_cdigo_postal_cp43_pattern.fullmatch(value))

# Example
print(validate_portuguese_cdigo_postal_cp43("1000-001"))  # 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

Portugal uses a CP4+3 (7-digit total, hyphen-separated) system. 1xxx (Lisbon), 4xxx (Porto), 8xxx (Algarve). CTT (Correios de Portugal) maintains the authoritative database. The hyphen is mandatory, unlike many other countries.