https://otvet.mail.ru/question/217553852

<?php
$array = ['+', '-', '/', '%'];
$totype = ['intval', 'floatval', 'strval', 'boolval',  /* 'arrayval'*/];
$from = $to = 10;
$min = 1;
$max = 100;
while ($i < $to) {
    $i++;
    $a = mt_rand($min, $max);
    $b = mt_rand($min, $max);
    $a = $totype[$i % count($totype)]($a);
    $b = $totype[$i % count($totype)]($b);
    foreach ($array as $index => $item) {
        $result = false;
        try {
            eval($str = '$result =' . '(' . $a . ')' . $item . '(' . $b . ')' . ';');
        } catch (Exception $e) {
            $Result[] = compact(['str', 'result', 'a', 'item', 'b', 'status' => $e->getMessage()]);
        }
        $Result[] = compact(['str', 'result', 'a', 'item', 'b', 'status' => true]);
    }
}
$tr[] = '<tr>';
$tr[] = '<th>#</th>';
$tr[] = '<th>a</th>';
$tr[] = '<th>тип (a)</th>';
$tr[] = '<th>операция</th>';
$tr[] = '<th>b</th>';
$tr[] = '<th>тип  (b)</th>';
$tr[] = '<th>=</th>';
$tr[] = '<th>тип (=)</th>';
$tr[] = '<th>str</th>';
$tr[] = '</tr>';
foreach ($Result as $index => $item) {
    $tr[] = '<tr>';
    $tr[] = '<td>' . $index . '</td>';
    $tr[] = '<td>' . $item['a'] . '</td>';
    $tr[] = '<td>' . (gettype($item['a'])) . '</td>';
    $tr[] = '<td>' . $item['item'] . '</td>';
    $tr[] = '<td>' . $item['b'] . '</td>';
    $tr[] = '<td>' . (gettype($item['b'])) . '</td>';
    $tr[] = '<td>' . $item['result'] . '</td>';
    $tr[] = '<td>' . (gettype($item['result'])) . '</td>';
    $tr[] = '<td class="str">' . $item['str'] . '</td>';
    $tr[] = '</tr>';
}
echo '<table align="center" class="table">' . implode(PHP_EOL, $tr) . '</table>
 <style>.table{border-collapse: collapse;  min-width: 960px} .table.th, table.td{border:1px solid  black; padding: 2px;} table  tr:nth-child(5n) td{background-color: #0b70db;}</style>';



echo '<table border=1>';
for ($i=0; $i<=255; $i += 50)
{
    echo '<tr>';

    for ($j=0; $j<=255; $j += 50)
    {
        for ($k=0; $k<=255; $k += 50)
        {
            echo '<td style="background-color:RGB('.$i.', '.$j.', '.$k.');"> rgb('.$i.', '.$j.', '.$k.')</td>';
        }
    }

    echo '</tr>';
}
echo'</table>';