How can PHP functions be made more flexible by returning true or false instead of text or HTML?

By having PHP functions return true or false instead of text or HTML, we can make them more flexible and reusable in different contexts. This allows the calling code to make decisions based on the boolean value returned by the function, rather than having to parse and interpret text or HTML output. This approach also simplifies the function's purpose to a binary result, making it easier to understand and maintain.

function is_valid_email($email) {
    if (filter_var($email, FILTER_VALIDATE_EMAIL)) {
        return true;
    } else {
        return false;
    }
}

$email = "example@example.com";
if (is_valid_email($email)) {
    echo "Email is valid.";
} else {
    echo "Email is invalid.";
}