While loop error when uploading $_FILES - php

Question

I'm looking to upload multiple files to a folder once all of the conditions are met successfully. I'm allowing the user to choose how many files they'd like to upload, however am receiving this error from the script:
Notice: Undefined offset: 1 in C:\xampp\htdocs\FreeCheese\news_parse.php on line 54
Note:
The number following 'Undefined offset:', in this case is set to '1'. When I chose to insert more file fields into the page this number becomes whatever the number of current file fields are being read by the PHP.
EG: I have three file fields, the error would then become:
Notice: Undefined offset: 3 in C:\xampp\htdocs\FreeCheese\news_parse.php on line 54
If I do select three files to upload, all of them are being correctly inserted into the folder, so I have no idea why I am being given an error when it is functioning as it should.
If anyone could help me fix this error then it'd be much appreciated.
Thanks in advance, Rich
Here is my code:
// Set the array object to 0 when entering the loop.
$i = 0;
while ($_FILES['upload1']['tmp_name'][$i]) {
$imgName1 = preg_replace("#[^a-z0-9.]#i", "", $_FILES['upload1']['name'][$i]);
// Applies a unique number before the file name to prevent files from overwriting.
$imgName1 = mt_rand(100000, 999999).$imgName1;
// Moves the image into the images/ folder
move_uploaded_file($imgTmp1[$i], "images/$imgName1");
// Sets the next array object in the loop to 1 etc etc
$i ++;
}

Answer 1

If there are 5 files, then $_FILES['upload1']['tmp_name'][5] won't exist, so the while condition crashes (it doesn't return false !)...
You have to check count($_FILES['upload1']['tmp_name']) !
$nbFiles = count($_FILES['upload1']['tmp_name']);
while ($i < $nbFiles) {
[...your code...]
$i++;
}
You should also use a for loop, since it is made for what you need :
$nbFiles = count($_FILES['upload1']['tmp_name']);
for ($i=0; $i < $nbFiles; $i++) {
[...your code...]
}