What are some essential PHP functions or methods for comparing and validating form field values, like email addresses?

When working with form submissions, it is crucial to compare and validate form field values, such as email addresses, to ensure data integrity and security. PHP provides several essential functions and methods for this purpose, including filter_var() for validating email addresses and strcmp() for comparing string values. 

// Validate an email address using filter_var()
$email = $_POST['email'];

if (filter_var($email, FILTER_VALIDATE_EMAIL)) {
    echo 'Email address is valid';
} else {
    echo 'Invalid email address';
}

// Compare two email addresses using strcmp()
$email1 = 'example1@example.com';
$email2 = 'example2@example.com';

if (strcmp($email1, $email2) === 0) {
    echo 'Email addresses match';
} else {
    echo 'Email addresses do not match';
}

Keywords

PHP form validation email validation filter_var strcmp

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