循环的迭代应该产生16个名字而不是4个

I have the loop below which iterates 4 times. Within this look is another which defines my group names. I would like to produce the output

Group 01
Group 02
Group 03
....
Group 15
Group 16

instead of what I currently get

Group 01
Group 02
Group 03
Group 04
Group 01
Group 02
Group 03
Group 04 
Group 01
Group 02
Group 03
Group 04
Group 01
Group 02
Group 03
Group 04

Code

foreach ($largegroups as $key => $users) { // loops 4 times
    for ($i = 1; $i <= 4; $i++) {
        $num = sprintf("%02d", $i);
        $groupname = 'Group ' . $num;
    }
}

You need to add a counter to the outer loop, and multiply that by 4 before adding $i to get the group number. For example:

$g = 0;
foreach ($largegroups as $key => $users) { // loops 4 times
    for ($i = 1; $i <= 4; $i++) {
        $num = sprintf("%02d", $g * 4 + $i);
        $groupname = 'Group ' . $num;
    }
    $g++;
}

You should declare and use a counter to calculate the correct number of a group. For example:

$counter = 0;
foreach ($largegroups as $key => $users) { // loops 4 times
    for ($i = 1; $i <= 4; $i++) {
        $counter++;
        $groupname = sprintf("Group %02d", $counter);
    }
}

Also, you can use range() function to generate group numbers and avoiding of nested loops. For example:

$count = count($largegroups) * 4;
foreach (range(1, $count) as $number) {
    $groupname = sprintf(" Group %02d", $number);
}

Two modifications:

1) Add a counter variable which iterates every time inner loop iterates. That is 4 X 4 = 16 times. Increment the counter at the beginning of inner loop. So that we start from 1 to end 16 instead of 0 to 15.

2) Add str_pad() function that will add leading 0 for counters less than 10. So Group 1 would become Group 01.

<?php 
$largegroups = ['','','',''];
$c = 0;
foreach ($largegroups as $key => $users) { // loops 4 times
 for ($i = 1; $i <= 4; $i++) {
  ++$c;
  $c = str_pad($c, 2, '0', STR_PAD_LEFT);
  echo "<br/>".$groupname = 'Group ' . $c;
 }
}

Output:

Group 01
Group 02
Group 03
Group 04
Group 05
Group 06
Group 07
Group 08
Group 09
Group 10
Group 11
Group 12
Group 13
Group 14
Group 15
Group 16

Working Example: