More of a theory question on uninitiated variables

[Vel]

This is more of a question of "is it OK and / or correct" and a point of interest to myself (and hopefully others) than anything else. I have a situation where in a multidimensional array I am counting the number of entries in another part of this array. I have this statement:

 

        if($array[$i]['counter'])
            $array[$i]['counter']++;
        else
            $array[$i]['counter'] = 1;

 

It would make sense to me to cut the code down and remove the if statement, and just go with:

 

        $array[$i]['counter']++;

 

Completely ignoring the step of checking to see if it's initialised, and if not initialising it. I'm guessing this isn't totally proper, but is it completely incorrect to do this or is it an acceptable way of saving a couple of lines of code?

[Adam]

Neither are actually correct. The first example will generate an 'undefined index' notice-level error if the key doesn't exist - you should be using isset. The second does not define the initial value, so what are you expecting to increment? Correct way is:

 

if (!isset($array[$i]['counter'])) {
    $array[$i]['counter'] = 0;
}

$array[$i]['counter']++;

[requinix]

Also, the correct way for the first example would be to use if(isset(...)) (like how Adam did, but without the ! because the logic is backwards).

[Vel]

Neither are actually correct. The first example will generate an 'undefined index' notice-level error if the key doesn't exist - you should be using isset. The second does not define the initial value, so what are you expecting to increment? Correct way is:

 

if (!isset($array[$i]['counter'])) {
    $array[$i]['counter'] = 0;
}

$array[$i]['counter']++;

Sorry, I mistyped it in my haste. I do use isset to check if it exists, and if it does increment it by 1, otherwise set it to 1.

[silkfire]

In PHP, even if null is evaluated as 0, something that is undefined will throw an error before you get the chance to increment it.

[Vel]

Thanks for the advice guys. I appreciate it.

[Adam]

In PHP, even if null is evaluated as 0, something that is undefined will throw an error before you get the chance to increment it.

 

Yeah, although even relying on those kind of false positive results such as null evaluating as 0 is a bad idea. You should always be over-explicit.

[hakimserwa]

You can also use a while loop.