How to use php empty function for this?

Good morning. Below is how my php formmail script processes my spam question. Whats the simplest way to write the same type of thing but only checking for if “name, phone, and email” inputs are NOT left empty? Thanks

So I just need to know how to write a simple if/else statement but checking for an empty field.

HTML Code:

---

if ($spam == 4){
    // success, continue processing
}
else{
    header( "Location: $errorurl" );
        exit ;
}

---

Use Google to search for PHP functions such as 'empty', 'isset', 'is_null()'

Empty is fine for text strings, but not for checkboxes, so you have to be careful how it is used.

if(empty($username)){
// the username was not entered ... it was left blank.
}

If I was doing your project and didn't know PHP very well, I might find an existing secure PHP/AJAX form script that is already written and proven.