Italian CAP (Codice di Avviamento Postale) Regex for PHP

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 PHP. A rigorously tested regex reduces debugging time and protects your application from edge-case failures. The snippet below is ready to drop into your PHP project — whether you're validating in a Laravel validator, a WordPress plugin, or a standalone PHP script.

Php Implementation

<?php
// Italian CAP (Codice di Avviamento Postale)
// ReDoS-safe | RegexVault — Localization > Postal Codes

define('ITALIAN_CAP_CODICE_DI_AVVIAMENTO_POSTALE_PATTERN', '/^(?!00000)[0-9]{5}$/');

function validate_italian_cap_codice_di_avviamento_postale(string $input): bool {
    return (bool) preg_match(ITALIAN_CAP_CODICE_DI_AVVIAMENTO_POSTALE_PATTERN, $input);
}

// Example
var_dump(validate_italian_cap_codice_di_avviamento_postale("00100")); // bool(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 PHP developers because especially relevant in PHP where PCRE backtracking limits can trigger silent failures on malicious input. 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.