Question

$hideCode = $likesObj->isAlreadyLikedByUser(facebookUID()) ? 'style="display:none;"' : '';

Can anyone explain to me what that question mark does in this line of code? Thanks a lot!

Answer 1

This is called the Ternary Operator, and it’s common to several languages, including PHP, Javascript, Python, Ruby…

$x = $condition ? $trueVal : $falseVal;

// same as:

if ($condition) {
    $x = $trueVal;
} else {
    $x = $falseVal;
}

One very important point to note, when using a ternary in PHP is this:

Note: Please note that the ternary operator is a statement, and that it doesn’t evaluate to a variable, but to the result of a statement. This is important to know if you want to return a variable by reference. The statement return $var == 42 ? $a : $b; in a return-by-reference function will therefore not work and a warning is issued in later PHP versions.
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