foreach cicle with math of previous row table - php

Question

Hello i need some help with this problem.
I'm printing a table with database values, but in one row field it will be math...
So like this example table.
<table style="border:1px solid black;">
<thead style="background:black;color:white;">
<th style="border:1px solid black;">date</th>
<th style="border:1px solid black;">debt</th>
<th style="border:1px solid black;">cred</th>
<th style="border:1px solid black;">result</th>
</thead>
<tbody>
<!-- foreach -->
<tr>
<td style="border:1px solid black;">01-10-2020</td>
<td style="border:1px solid black;">1000</td>
<td style="border:1px solid black;">100</td>
<!-- the follwing result is 1000-100 -->
<td style="border:1px solid black;">900</td>
</tr>
<tr>
<td style="border:1px solid black;">02-10-2020</td>
<td style="border:1px solid black;">0</td>
<td style="border:1px solid black;">200</td>
<!-- the follwing result is (0-200)+900 -->
<td style="border:1px solid black;">700</td>
</tr>
<tr>
<td style="border:1px solid black;">03-10-2020</td>
<td style="border:1px solid black;">150</td>
<td style="border:1px solid black;">0</td>
<!-- the follwing result is (150-0)+700 -->
<td style="border:1px solid black;">850</td>
</tr>
<!-- end foreach -->
</tbody>
</table>
So i expect the result field with this formula (debt - cred)+previous result of the row before, the first row the is (debt-cred)+0...and the maths star after the first row.

Answer 1

This might help you along, slightly back to front of what you have:
<?php
$data =
[
[100, 20],
[20, 0],
[0, 50]
];
$balance = 0;
foreach($data as $row) {
$balance += $row[0] - $row[1];
printf("Cred: %d, Debt: %d, Balance: %d.\n", $row[0], $row[1], $balance);
}
Output:
Cred: 100, Debt: 20, Balance: 80.
Cred: 20, Debt: 0, Balance: 100.
Cred: 0, Debt: 50, Balance: 50.