Is this the syntax for an IF-THEN-ELSE?

[tbode2021]

<input class="form-check-input" type="checkbox" id="a201" name="a201" value="a">
<label class="form-check-label" for="a201">Acetaminophen</label> 

$score = (isset($_POST['a201']) && $_POST['a201']=='a')? 1 : 0;

So if checkbox is checked and has the value of 'a', $score gets assigned the value of 1. Otherwise $score gets assigned the value of 0?

[maxxd]

It's a shorthand for if:else called a ternary operator. You'll have to scroll down the link for the full explanation as apparently there's not a name link there.

Your reading of the line is correct, yes - a checkbox variable will only exist in $_POST when it's checked; so if it's checked and equal to 'a' $score will be 1, otherwise $score will be 0.

[Barand]

Another way is to give the checkbox form input the value you actually want when it is set (ie "1")

<input class="form-check-input" type="checkbox" id="a201" name="a201" value="1">

then

$score = $_POST['a201'] ?? 0;

which means "if the checkbox exists and is not null, use its value, otherwise default to "0". (See Null Coalesce operator)