Creating a multiplication "grid" - php

Question

I am trying to create a simple multiplication grid in PHP
It should be of the format for example for a 2x2 grid:
0 1 2
1 1 2
2 2 4
My issue is getting it to start from 0.
This is my nested for loop so far:
for($i=0;$i<=$_POST['rows'];$i++)
{
echo "<tr>";
for($j=0;$j<=$_POST['columns'];$j++)
{
if($i==0)
{
echo "<td>" . 1*$j . "</td>";
}
else
{
$mult = $i * $j;
echo "<td> $mult </td>";
}
}
echo "</tr>";
}
But it gives the output:
0 1 2
0 1 2
0 2 4
I need the column of 0's to be appropriate.

Answer 1

The way you're getting the top row of 0 1 2 3 is by that special-case on the X-axis. Do a similar special-case for the Y-axis ($j):
if ($i == 0) {
... 1 * $j ...
}
else if ($j == 0) {
... $i * 1 ...
}
else {
... $i * $j ...
}

Answer 2

You not only have $i==0 as special case but also $j==0:
if($i==0)
{
echo "<td>" . 1*$j . "</td>";
}
elseif($j==0)
{
echo "<td>" . $i*1 . "</td>";
}
else
{
$mult = $i * $j;
echo "<td> $mult </td>";
}

Answer 3

I don't understand the way you construct your grid. All you need is a row indicator and the number for the multiplication not a nested loop. Second: Why don't you start with 1 instead of catching the case inside the loop. This would be my variant of the multiplication “grid”
<?php
$rows = $_POST['rows'];
$number = $_POST['columns'];
for( $i=1; $i <= $rows; $i++) {
$mult = $i * $number;
echo "<tr>
<td>" . $i.'*'. $j . "</td>
<td>".$mult."</td>
</tr>";
}
?>
This would to a simple grid (x * y) = result. If you want a complete multiplication table it would be something like this:
<?php
$rows = $_POST['rows'];
$number = $_POST['columns'];
echo "<tr><th></th>";
for( $j=1; $j <= $number; $j++) {
echo "<th>".$j."</th>";
}
echo "</tr>";
for( $i=1; $i <= $rows; $i++) {
echo "<tr>";
echo "<th>".$i."</th>";
for( $j=1; $j <= $number; $j++) {
$mult = $i * $j;
echo "<td>".$mult."</td>";
}
echo "</tr>";
}
?>