What are the best practices for validating form input in PHP to ensure compatibility with special characters?

When validating form input in PHP to ensure compatibility with special characters, it is important to sanitize the input data to prevent potential security vulnerabilities such as SQL injection or cross-site scripting attacks. One common approach is to use PHP's filter_input function with the FILTER_SANITIZE_STRING flag to remove any potentially harmful characters from the input. 

$input = filter_input(INPUT_POST, 'input_field', FILTER_SANITIZE_STRING);
if ($input === false) {
    // Input validation failed
    // Handle the error accordingly
} else {
    // Input validation successful
    // Proceed with processing the sanitized input
}

Keywords

htmlspecialchars filter_input regex htmlentities validation

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