Form Validation with Regex

Regex Form Validation

Use regex to validate form inputs in PHP. Combine with PHP's filter functions for comprehensive validation.

Example

<?php
function validateForm(array $data): array {
    $errors = [];

    // Email
    if (!filter_var($data["email"], FILTER_VALIDATE_EMAIL)) {
        $errors["email"] = "Invalid email";
    }

    // Phone (US format)
    if (!preg_match("/^\(?\d{3}\)?[-.\s]?\d{3}[-.\s]?\d{4}$/", $data["phone"])) {
        $errors["phone"] = "Invalid phone number";
    }

    // Password strength
    if (!preg_match("/^(?=.*[A-Z])(?=.*[a-z])(?=.*\d).{8,}$/", $data["password"])) {
        $errors["password"] = "Password must be 8+ chars with upper, lower, and digit";
    }

    return $errors;
}

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Pro Tip

Use PHP's filter_var() for email/URL/IP validation — it is more accurate than most hand-crafted regex.

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