Could you find the difference in results between these two codes?
function getStatusByCode($code)
{
$status = '';
switch ($code) {
case 0:
$status = 'OK';
break;
case 1:
$status = 'WARNING';
break;
default:
$status = 'UNDEFINED';
break;
}
return $status;
}
var_dump(getStatusByCode(null));
and
function getStatusByCode($code)
{
$status = '';
if ($code === 0) {
$status = 'OK';
} elseif ($code === 1) {
$status = 'WARNING';
} else {
$status = 'UNDEFINED';
}
return $status;
}
var_dump(getStatusByCode(null));
So have you found it?
- In the first case with the
switch, the method returnsOK. - In the second case, the method returns
UNDEFINED.
But why this difference?
The first code with the switch comes from a legacy code base: no type hinting on the arguments, no return from the function. And this code was the cause of a small bug, because switch uses loose comparison: using == instead of === to compare values.
And in PHP with the loose comparison, null equals 0.
So be careful when you have a sequence of if / elseif / else, switching to switch can have an impact on the expected behavior.
So what to do?
If you follow me a little, I recommend that you use the strict comparison with === most often (if not all the time).
So if you want to keep this behavior, some ideas:
- You leave your sequence of
if/elseif/else - You reinforce your function parameters with types to ensure you never have an unwanted value (if that's the case)
function getStatusByCode(int $code)
{
$status = '';
switch ($code) {
case 0:
$status = 'OK';
break;
case 1:
$status = 'WARNING';
break;
default:
$status = 'UNDEFINED';
break;
}
return $status;
}
var_dump(getStatusByCode(null));
/* Result : Fatal error: Uncaught TypeError:
* Argument 1 passed to getStatusByCode() must be of the type int, null given
*/
- You are using
matchavailable since PHP 8 which uses strict comparison π
function getStatusByCode($code)
{
return match($code) {
0 => 'OK',
1 => 'WARNING',
default => 'UNDEFINED',
};
}
Thank you for reading, and let's stay in touch !
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Top comments (5)
Wow! This
matchis cool!Isn't it better to use an ENUM?
The example is here to show the difference between loose comparaison (switch) and strict comparaison.
Enum or not, you will probably encountered a switch case in your code, and the goal here is to warn people of the loose comparaison.
Hmmm, this part is well explained, great job!
Didn't know
switchuses loose comparison, thank you for the advice!