Validate if age is over 18 years old

Question

Just wondering, can I do this to validate that a user has entered a date over 18?

//Validate for users over 18 only
function time($then, $min)
{
    $then =          


        

Answer 1

HTML Input:

PHP code:

function validateDateOfBirth($birthDay)
    {
// convert user input date to string and +18 years;
// compare user input date with current date;

        if (time() < strtotime('+18 years', strtotime($birthDay))) {
            return 'Not 18';
        }
        return "user is older than 18 years old";
    }