What does this mean? $length = null === $length ? strlen($data) : (int)$length ;

Question

I'm aware of ternary operator, more or less. But I'm unable to read this line.

$length = null === $length ? strlen($data) : (int)$length ;

What does $length = null === $length means?

Thanks a lot, MEM

Answer 1

It's the equivalent of

if (null === $length)
  $length = strlen($data);
else
  $length = (int)$length;

Answer 2

It means:

If the value of $length is null, assign strlen($data) to $length, otherwise (int)$length.

---

It is easier to understand if parenthesis are put at the right place:

$length = (null === $length) ? strlen($data) : (int)$length ;

Answer 3

This is basically the same as

if ($length === null)
{
    $length = strlen($data)
}
else
{
    $length = (int)$length;
}

Answer 4

It means

if (null === $length) {
   $length = strlen($data);
} else {
   $length = (int)$length ;
}

Answer 5

$length = (null === $length ? strlen($data) : (int)$length ) ;


if (null === $length) {
  $length = strlen($data);
} else {
  $length = (int)$length;
}

The === means that $length must be exactly null. See PHP Comparison Operators.

Answer 6

It's the same as $length = (null === $length ? strlen($data) : (int)$length );

Answer 7

Adding a couple of parenthesis should make it clear:

$length = (null === $length ? strlen($data) : (int)$length);

Also the use of null === $length instead of $length === null is just coding style, mainly used to ne against stupid compilers that don't warn you about something like if (foo = null) { instead of if (foo == null) {.

Answer 8

a === b means a is identical to b and they are of the same type.

So if $length === null then $length = strlen($data) else $length