What are the potential issues with using special characters in input names in PHP forms?

Special characters in input names in PHP forms can potentially cause issues with data validation, processing, and security. To avoid these problems, it is recommended to sanitize input names by removing special characters and only allowing alphanumeric characters and underscores.

// Sanitize input names by removing special characters
$input_name = preg_replace('/[^a-zA-Z0-9_]/', '', $_POST['input_name']);