Alternating table row background colors on a dynamic table

Question

I have a table generated by a foreach loop.

Before the loop, I create $iteration = 0 . At the beginning of the loop it increments $iteration .

Then I do this:

if($iteration % 2 == 0) { 
  $greyRow = 'css for a grey row'; 
}

I've only three rows, at max, to test this with, but it seems that it greys the 2nd and 3rd row under the current rule, rather than only the second.

Answer 1

This following will add a grey class for even rows.

echo '<tr', ($iteration & 1 ? ' class="grey"': ''), '>';

Note

This uses a bitwise operator . It's a micro-optimization but far more optimal than the modulus operator (although notoriously used in these cases).

Also, I would encourage you to utilize CSS classes for even and odd rows versus inline styles or just toggling a single class (ie grey ).

echo '<tr class="', ($iteration & 1 ? 'even': 'odd'), '">';

Answer 2

Perhaps you also need to have an else statement to set back to the other color on the odd rows. Not quite sure without seeing more of your implementation.

if ($iteration % 2 == 0) {
    $css = 'css for a grey row';
} else {
    $css = 'css for a white row';
}

Answer 3

I like to do this kind of thing..

<style type="text/css">
.odd td { background: #eee; }
</style>
<tr class="<?= ++$iteration % 2? 'odd' : 'even'; ?>">....</tr>