Unsure what PHP array is doing upon assigning

Question

I have a DB snippit of code here... I'll post the relevant lines without error checking to make it smaller...

if ($stmt->bind_result($row[0], $row[1]) === false) etc...

then below I have...

<pre><code>
    //fill the array up with an array of rows, then increment $ddp.
    //$data[$ddp] is the row,
    //$data[$dpp][0] is the rows first argument,
    //$data[$dpp][1] is the rows 2nd argument returned etc...

    $ddp = 0; // this increments up every fetch

    while ($stmt->fetch()) {
        $data[$ddp][0] = $row[0];
        $data[$ddp][1] = $row[1];
        $ddp++;
    }
</code></pre>

The way I have it above WORKS.... but here is how I did it before and something weird was happening...

<pre><code>
    $ddp = 0; // this increments up every fetch

    while ($stmt->fetch()) {
        $data[$ddp++] = $row;
        // I ECHOd out $row here... and it did fetch 2 different rows...
    }
</code></pre>

What happens is... when I did this...

$data[$ddp++] = $row;

$data[0][0] was the same as $data[1][0] .

Why then if $row had different values on the 2 fetches... how did $data end up with 2 arrays the same?

I even tried

$data[] = $row;

and the same results. My fix was...

while ($stmt->fetch()) {
    $data[$ddp][0] = $row[0];
    $data[$ddp][1] = $row[1];
    $ddp++;
}

WHY?

Sorry if this isn't the right place to put this but I did find a solution ahead of time and to save time I posted the answer and my question together.

Answer 1

Your two assignments are doing two subtly different things.

while ($stmt->fetch()) {
    $data[$ddp][0] = $row[0];
    $data[$ddp][1] = $row[1];
    $ddp++;
}

This creates two entries in the array - the first will have the index [0][0] , and be assigned the value in $row[0] , and so on.

On the other hand, this:

while ($stmt->fetch()) {
    $data[$ddp++] = $row;
    // I ECHOd out $row here... and it did fetch 2 different rows...
}

is adding a single row to the database, and adding the whole of $row to $data[0] on the first run through. So whatever is returned from the database is added as it is - if you're getting an array back from fetch() , then you're adding an array inside your array.