Why there is an undefined offset in this array?

Question

I want to store some data in an array called $temp, but I got an error that there is an undefined offset. Here's my code:

$temp    = array();
$terms   = $this->DocumentTerms();
$temp[0] = $terms[0][0];

for ($i = 0; $i < sizeof($terms); $i++) {

    $flag = true;

    for ($j = 0; $j < sizeof($terms[$i]); $j++) {

        for ($k = 0; $k < sizeof($temp) || $k < sizeof($terms[$i]); $k++) {

            if ($temp[$k] == $terms[$i][$j]) {

                $flag = false;
                break;
            }
        }

        if ($flag)
            array_push($temp, $terms[$i][$j]);
    }
}

The undefined offset is at this part:

if($temp[$k] == $terms[$i][$j])

As an aside, any particular reason you chose to use sizeof() vs count()? — summea
– summea, Commented Apr 17, 2014 at 17:49
@summea: sizeof() is an alias of count(). They're exactly the same. — Amal
– Amal, Commented Apr 17, 2014 at 17:50
@summea: Ah, okay. Maybe they're from a C(++) background, but that's just a guess :-) — Amal
– Amal, Commented Apr 17, 2014 at 17:54

Sam · Accepted Answer · 2014-04-17 17:50:10Z

3

This conditional:

$temp[$k] == $terms[$i][$j]

Should be:

isset($temp[$k]) && $temp[$k] == $terms[$i][$j]

You don't push any data to $temp until the end of the second loop, but you try to access the $kth index of the array in this conditional. If it hasn't been set yet, it will fail. Check to make sure it is set and then continue on with seeing if it equals $terms[$i][$j].

answered Apr 17, 2014 at 17:50

Sam

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4 Comments

Jason OOO Over a year ago

or array_key_exists($k,$temp)

Sam Over a year ago

Yup @JasonOOO, I usually leave that one up to personal preference. I guess array_key_exists() is more obvious as to what you are trying to do, but I like using isset() for consistency across the board. Do you know of any performance differences?

Amal Over a year ago

+1: But I wouldn't say func(condition) && $var = $stuff; is the best way to write this. It works, but I'd expand it to a full statement using the ternary operator.

Sam Over a year ago

Very true @AmalMurali. I think breaking it up is easiest for explaining what broke and how it is fixed, so I'm going to leave my answer as is.

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