无法用三元运算符复制条件

Question

I'm trying to replicate this condition:

$sth = $this->getResult();
if($sth !== true){
   return $sth;
}

with ternary operator I tried with;

($sth !== true) ?  return $sth : ($sth == true) ? null;

But I got:

Expected colon

Answer 1

What you're ultimately trying to achieve is not possible with a ternary operator.

What you try to do is ONLY return in 1 situation, and continue the code in the other. The only way you could do this using a ternary operator is like this:

$result = ($sth !== true) ? true : false;
if ($result) return;

But that kinda defeats the purpose of the ternary operator.

---

In fact, your code has a couple of problems:

• Ternary operator always needs 3 parts (*)
• There is no need to check a condition twice, as that's the entire point of the operator
• The operator returns a value, so you can't put a return inside the truthy or falsy part.

A ternary operator needs 3 parts

(condition) ? truthy result : falsy result

Note: Since PHP 5.3, it is possible to leave out the middle part of the ternary operator. Expression expr1 ?: expr3 returns expr1 if expr1 evaluates to TRUE, and expr3 otherwise. - source: php.net

No need to check things twice:

Again, let's take our operator:

($sth !== true)
                ? "I return if '$sth' is not true"
                : "I return if '$sth' is true";

There is no need to have a 2nd check. You have both situations covered already. :)

No return values inside the truthy or falsy part

Finally: it is an operator that returns a value. You can't put a return in the truthy or falsy part, you need to put it in front of it:

return ($sth !== true)
                ? "I return if '$sth' is not true"
                : "I return if '$sth' is true";