Why do I get undefined index while using simple array function

Question

This is my example array:

$arrayy[0]=48.72;
$arrayy[1]=21.32;
$arrayy[2]=48.62;
$arrayy[3]=21.31;
$arrayy[4]=48.62;
$arrayy[5]=21.31;

This function

function writeDouble($array){
        for($curr = 0; $curr<count($array)-1; $curr++){
            echo $array[$curr]." - ";
            echo $array[$curr+1]."<br>";
            $curr++;
    }
}

should write a couples (0-1 , 2-3 , 4-5) - an output like:

48.72 - 21.32
48.62 - 21.31
48.62 - 21.31

What am I doing wrong, why do I got an error?

Notice: Undefined offset: 6 in C:\xampp\htdocs\xampp\lg\functions.php on line 466

Or could you define a better function to make couples? I can't think anymore... thanks

Yes. They are always even... hmm, ok. But why do I have this offset on my server? — user1666761, Sep 16 '12 at 17:20
Your code works fine according to this: http://codepad.org/cHdWSMMm. — Kenny Linsky, Sep 16 '12 at 17:24

score 4 · Answer 1 · answered Sep 16 '12 at 17:15

4

Because in the last iteration in line echo $array[$curr+1]."<br>"; you'll be looking for $array[count($array)] which is ofcource not defined!!

answered Sep 16 '12 at 17:15

Rajat Singhal

11,234
5
38
56

I subtracted "1" (-1) from size of cycle count($array) . – user1666761 Sep 16 '12 at 17:19
@user1666761 - But in the last iteration, $curr will be count($array)-1, which means $curr+1 will be one greater than count($array)-1 – Mark Baker Sep 16 '12 at 17:23
So, what do you suggest? After removing -1, error still stays. – user1666761 Sep 16 '12 at 17:25
iterating until count($array) -2 – artragis Sep 16 '12 at 18:02

score 0 · Accepted Answer · edited Sep 16 '12 at 18:40

You're using $array[$curr + 1] but you're iterating from 0 to $curr - 1. You need an isset in case you have an odd number of values in your array.
You're incrementing 2 times (one time in your for, one time in the scope of your for).

Code solution:

$arrayy[0]=48.72;
$arrayy[1]=21.32;
$arrayy[2]=48.62;
$arrayy[3]=21.31;
$arrayy[4]=48.62;
$arrayy[5]=21.31;    

function writeDouble($array) {
        for ($curr = 0; $curr < (count($array) - 1); $curr += 2) {
            echo $array[$curr] . " - ";
            if (isset($array[$curr + 1])) {
              echo $array[$curr + 1];
            }
            echo "<br>";
    }
}

writeDouble($arrayy);

Output:

48.72 - 21.32
48.62 - 21.31
48.62 - 21.31

No more warning.

Ok, works.. as my example. Because warning was from different function :-) I'm kinda distracted today, thanks — user1666761, Sep 16 '12 at 17:39

score 0 · Answer 3 · answered Sep 16 '12 at 17:24

0

Note that you are incrementing $curr two times:

for($curr = 0; $curr<count($array)-1; $curr++){

and

$curr++

This is the reason for going out of range in your loop

answered Sep 16 '12 at 17:24

Hernan Velasquez

2,770
14
21

Because I need to do couples. So increment need to be by 2. – user1666761 Sep 16 '12 at 17:31
Oh I understand. And thinking it better this is not the reason for an undefined index. Make a var_dump($array) and check if the array is built as you state in your question. – Hernan Velasquez Sep 16 '12 at 17:37

Why do I get undefined index while using simple array function

3 Answers3