Issue with modulo and array index in php

I'd suggest switching to using a counter variable, also, you'll need to rethink the last part of it, because unless it ends on a multiple of 4, it's not gonna give you the final /tr either.

Here's how I'd do it, and I'd also get rid of those awful ternary operators:

<table width="80%" border="1">
<?php
$i = 1;
foreach($projects as $index=>$project)
{
    if($i == 1)
    {
          echo '<tr>';
    }

    echo '<td>' . anchor('project/view/'.$project->id, $project->project_name, 'title='.$project->project_name) . '</td>';

    if($i == 4)
    {
          echo '</tr>';
          $i = 0;
    }

    $i++;
} 

if($i != 1) //Catch it if it doesn't end evenly, since $i will == 1 if it ended on a multiple of 4
{
     while($i <= 4) //Create empty cells to even table out, table will quite possibly look funky otherwise 
     {
         echo '<td></td>';
         $i++;
     }
     echo '</tr>'; //End table row
}
?>
 </table>

If you want it to look nice, append PHP_EOL or "\n" to the end of each echo statement. If you want it to look really nice, you could prepend "\t" to certain echo statements to give it the look of a manually indented and hand coded html.

My preferred solution for things like this is breaking it out into a helper function (codeigniter details). It keeps the markup cleaner and makes sure that after you've solved it once you don't have to rethink it.

Here's a crack and what you're after. It will return a multidimensional array of rows that you can iterate over.

function rowify($array, $perRow) {
    $currentRow = 0;
    $counter = 0;
    $new = array();
    foreach ($array as $key => $element) {
        if ($counter % 4 == 0) {
            ++$currentRow;
            $new[$currentRow] = array();
        }
        $new[$currentRow][$key] = $element;
        ++$counter;
    }
    return $new;
}

Using this, your markup will look like:

<table width="80%" border="1">
<?php foreach(rowify($projects,4) as $row) : ?>
  <tr>
    <?php foreach ($row as $index=>$project):?>
      <td>
        <?php echo anchor('project/view/'.$project->id, $project->project_name, 'title='.$project->project_name); ?>
      </td>
    <?php endforeach; ?>
  </tr>
<?php endforeach; ?>
 </table>

which I think is quite elegant - no if statements, no echo ''; stuff, just iteration.

At the moment, you're adding a tr at the beginning of every fourth cell, and a end tr at the end of every fourth cell. The end tr needs to be added after the fourth cell, and the tr should be added before the fifth one.

Think about it - you're using the exact same logic check to place the opening <tr> as the closing </tr>. This means that every 4th element will be surrounded by an opening row tag and a closing row tag.

if it helps - here is some old code I dug out that does it - not codeigniter but should guide you - have taken my db stuff out to clean it up:

define('NUMCOLS', 4);
$count = 0;
$counter = 1;
//create table
echo '<table width = \"100%\" border = 1 cellpadding = 0>';
//create a table row for each book   
foreach ($book_array as $row)
{
  // get your data
  if($count % NUMCOLS == 0) //new row
    echo '<tr>';
    echo'<td>';
    // display data
    echo '</td>';
    $count++;
   $counter++;
  if($count % NUMCOLS ==0)
    echo '</tr>'; //end row
}
echo '</table>';
}
}