Question Mark ?

? is a character, used in various situations:

• Ternary operator: $a ? $b : $c

• Short ternary operator: $a ?: $c

• Coalesce operator: $a ??

• Null type, function foo(?int $int) {}

• As a quantifier in regex, 0 or 1

• As a quantifier with fnmatch(), 0 or 1.

<?php

    $a = 1;
    echo a ? 'b' : 'c'; // c

?>

Related : Ternary Operator, Coalesce Operator, Type System, Regular Expression, fnmatch()