What is the correct usage of single and double quotes within input fields in PHP?

When using input fields in PHP, it is important to properly handle single and double quotes to avoid syntax errors or injection attacks. To ensure the input is secure and correctly processed, it is recommended to use htmlspecialchars() function to encode special characters and prevent script injections. This function will automatically convert both single and double quotes into their respective HTML entities, ensuring the input is safe to use in your PHP code.

// Example of using htmlspecialchars() function to handle single and double quotes in input fields
$input = $_POST['input_field']; // Assuming input comes from a form submission

$clean_input = htmlspecialchars($input, ENT_QUOTES); // Encode both single and double quotes

// Now $clean_input can be safely used in your PHP code without worrying about quotes