Weird incremented query result in a while - php

Question

I don't understand why the result of the '$taille' array begin to the key [1] instead of key [0]? So it s displaying 3 results instead of 4 (occulting the first result)...
<?php
$req = $bdd->prepare('SELECT size FROM tailles_produits WHERE id_produit = ?');
$req->execute(array($_GET['id']));
$donnees = $req->fetch();
$numb_taille = array();
$taille = array();
$i = 0;
while($donnees = $req->fetch())
{
$i++;
$taille[$i] = $donnees['size'];
$numb_taille['total'] = $i;
}
$total = $numb_taille['total'];
echo '<pre>';
print_r ($taille);
echo '</pre>';
$req->closeCursor();
?>
Which gives
ARRAY
(
[1] => S
[2] => M
[3] => L
)
Instead of
ARRAY
(
[1] => XS
[2] => S
[3] => M
[4] => L
)
Can anyone help me with this pleas?

Answer 1

PHP arrays start with 0, so all you need to do is move your i++ down until after you're done using the data from that index
<?php
$req = $bdd->prepare('SELECT size FROM tailles_produits WHERE id_produit = ?');
$req->execute(array($_GET['id']));
$donnees = $req->fetch();
$numb_taille = array();
$taille = array();
$i = 0;
while($donnees = $req->fetch())
{
$taille[$i] = $donnees['size'];
$numb_taille['total'] = $i;
$i++; //iterate after your calculations are done
}
$total = $numb_taille['total'];
echo '<pre>';
print_r ($taille);
echo '</pre>';
$req->closeCursor();
?>

Answer 2

The problem is that you have an extra
$donnees = $req->fetch();
statement before the loop that fills in $taille. So the data from the first row is being fetched but not stored in the array.

Answer 3

It is because you increment $i before using it as a key for the new array item.
Do the increment at the end of your while loop.