What is this syntax in PHP?

Question

I'm working on modifying a script to better suit my needs, and I came across this line in the code:

return isset($_COOKIE[$parameter_name]) ? $_COOKIE[$parameter_name] : "";

I know that the function itself is essentially a cookie getter method, but I'm not quite sure what that syntax (i.e. the "?" and ":") means. I apologize if this is a really dumb question, but could someone explain it to me?

Answer 1

It's a ternary operation and is basically a more compact way of writing an if/then/else.

So in your code sample it's being used instead of having to write:

if (isset($_COOKIE[$parameter_name])) {
    return $_COOKIE[$parameter_name];
} else {
    return "";
}

Answer 2

It's a ternary operation which is not PHP specific and exists in most langauges.

(condition) ? true_case : false_case 

And in my opinion should only be used as short one liners like in your example. Otherwise readabilty would suffer – so never nest ternary operation (though it's possible to do so).