Multi For loop php - php

Question

How to use multi for loop with array.
I'm trying to iterate over the contents of an array.
This is the code I have tried.
<?php
$arr = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15];
for($i = 0; $i < 5; $i++){
echo $arr[$i];
for($j = 0; $j < $i; $j++){
echo $arr[$j];
}
echo "<br />";
}
echo "<br/>";
for ($i = 0; $i <= count($arr); $i++){
if ($i%3 == 0){
echo $arr[$i-1] . " " . "<br />";
} else {
echo $arr[$i-1] . " ";
}
}
this is the result i got
1
2 1
3 1 2
4 1 2 3
5 1 2 3 4
1 2 3
4 5 6
7 8 9
10 11 12
13 14 15
I want to display a result like this and how it works:
1
2 3
4 5 6
7 8 9 10
11 12 13 14 15
1 | 6 | 11
2 | 7 | 12
3 | 8 | 13
4 | 9 | 14
5 | 10 | 15
Thank you

Answer 1

Two separate questions:
The first one, I'd do like this:
$arr = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15];
$prev =0;
for ($i=1; $i<=5; $i++) {
print implode(" ", array_slice($arr, $prev, $i)) . "<br>\n";
$prev += $i;
}
You could replace the array_slice() with a for loop if that makes you happier. The second one:
$cols = 3;
$rows = floor(count($arr)/$cols);
for ($i = 0; $i < $rows; $i++) {
for ($j=0; $j<=$cols; $j++) {
print $arr[$i+$j*$rows] ?? ' ';
if ($j < ($cols-1)) print " | ";
}
print "<br>\n";
}