nested php ternary trouble: ternary output != if - else [duplicate]

Answer 1

The code is executed as

$decimal_places = (($max <= 1) ? 2 : ($max > 3)) ? 0 : 1;

so you'll never get 2 and 1 only when 1 < $max <=3. This is because the conditional operator is left-associative. Solution: Place parentheses to make sure the order you want is coded:

$decimal_places = ($max <= 1) ? 2 : (($max > 3) ? 0 : 1);

Answer 2

As others pointed out, use paranthesis.
However, if you actually want to make it readable, what about this:

$decimal_places =
  ($max <= 1) ? 2 : (
  ($max > 3)  ? 0 : (
  1
));

This still looks super awkward, but this awkwardness has a regular shape, so it's easier to live with.

$drink = 'wine';
return
  ($drink === 'wine')   ? 'vinyard' : (
  ($drink === 'beer')   ? 'brewery' : (
  ($drink === 'juice')  ? 'apple tree' : (
  ($drink === 'coffee') ? 'coffeebeans' : (
  'other'
))));

You could of course omit the last pair of brackets, but that would make it less regular-looking.

Answer 3

Your right-hand-side ternary expression needs to be wrapped in parentheses so it'll be evaluated by itself as a single expression:

$decimal_places = ($max <= 1) ? 2 : (($max > 3) ? 0 : 1);

// Another way of looking at it
$decimal_places = ($max <= 1)
                ? 2
                : (($max > 3) ? 0 : 1);

Otherwise your ternary expression is evaluated from left to right, resulting in:

$decimal_places = (($max <= 1) ? 2 : ($max > 3)) ? 0 : 1;

// Another way of looking at it
$decimal_places = (($max <= 1) ? 2 : ($max > 3))
                ? 0
                : 1;

Which, translated to if-else, becomes this:

if ($max <= 1)
    $cond = 2;
else
    $cond = ($max > 3);

if ($cond)
    $decimal_places = 0;
else
    $decimal_places = 1;

Therefore $decimal_places ends up as 0 for all values of $max except 2, in which case it evaluates to 1.

Answer 4

Just put the parenthesis and you would be fine, like this:

 $decimal_places = ($max <= 1) ? 2 : (($max > 3) ? 0 : 1);