How can PHP be used to validate and sanitize user input from a contact form before processing it?

When processing user input from a contact form in PHP, it is important to validate and sanitize the data to prevent security vulnerabilities such as SQL injection or cross-site scripting attacks. This can be achieved by using PHP functions like filter_var() to validate input data against predefined filters, and functions like htmlspecialchars() to sanitize input data by converting special characters to HTML entities. 

// Validate and sanitize user input from a contact form
$name = filter_var($_POST['name'], FILTER_SANITIZE_STRING);
$email = filter_var($_POST['email'], FILTER_VALIDATE_EMAIL);
$message = htmlspecialchars($_POST['message']);

// Process the sanitized input data
// Additional code to handle the contact form submission

Keywords

PHP validation sanitization user input contact form

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