php: how to add odd/even loop in array

Question

Due to comment below, here is the code on pastebin: http://pastebin.com/m6b0bb378

Here is the full script, if anyone wants to get it to do what i need in full, as i'm not a ocder so i'm getting lost here: http://pastebin.com/m6e8a5f5d

With the help of scragar, i've got to the above stage. The problem is that the "odd" part is only showing up for the first iteration, all others are using even, so something is wrong.

Hoping someone can help me correct this so odd/even works properly.

Answer 1

I haven't looked over the code, but if it's using a variable to count the loop number you can do:

 for($i=0;$i<$blah;$i++)
   if($i&1){
     // ODD
   }else{
     // EVEN
   }

EDIT(1): I looked at the section you are running into, and now I have another problem, I'm unsure how you are judging what should be odd or not, so I propose two answers:

1: odd loop itteration:

   /* Populate the post list array */
// Add here:
   $oddLoop = false;
   foreach ($findposts as $findpost):
//.....
if($oddLoop=!$oddLoop){
  // code for odd loop numbers
}else{
  // code for even loop numbers
}

2: Odd ID number:

 } elseif ( ( $findpost->ID ) != $id ) {
    if($findpost->ID & 1){
       // ODD
    }else{
       //EVEN
    }

Answer 2

The three ways are

Modulo

for ($i = 0; $i < 10; $i++)
{
  if ($i % 2 == 0)
  {
    echo "even";
  }
  else
  {
    echo "odd";
  }
}

Flipping boolean value

$even = true;
for ($i = 0; $i < 10; $i++)
{
  if ($even)
  {
    echo "even";
  }
  else
  {
    echo "odd";
  }

  $even = !$even;
}

And mentioned boolean operator

for ($i = 0; $i < 10; $i++)
{
  if ($i & 1 == 0)
  {
    echo "even";
  }
  else
  {
    echo "odd";
  }
}

The most fastest is boolean operator. But the most robust is flipping method if you have very different numbers (like running through ID numbers and some are missing).

Answer 3

Are you sure $findpost->ID contains sequential numbers?

You could replace the if/else with s short ternary statement like this:

$side = empty($side) || $side == 'right' ? 'left' : 'right';
$serp_list_li[] = '<div class="serial-contain-' . $side . '">' // ...the rest

This would add a 'left' side first.

Answer 4

If you ever delete an article you could be in trouble - your code assumes that ID runs (odd,even,odd,even) etc.

A better idea would be to create a separate iterator object to feed you the necessary values at each step. Here's what I use:

class LoopingPropertyIterator implements Iterator {
 private $startat=0, $position=0;
 private $propertylist=array(
  'boolean' => array( false, true ),
  'day' => array('Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'),
  'dow' => array('Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat')
 );

 public function __construct($args, $startat=0) {
  $this->startat = (int) $startat;
  $this->position = $this->startat;

  foreach($args as $name => $arr)
   $this->__set($name, $arr);
 }

 public function __get($name) {
  if (!array_key_exists($name, $this->propertylist))
   throw new Exception(__METHOD__." unknown property $name");

  $t =& $this->propertylist[$name];

  if (is_array($t))
   return $t[ $this->position % count($t) ];
  else
   return $t;
 }

 public function __set($name, $arr) {
  $this->propertylist[$name] = $arr;
 }
 public function current() { return $this->position; }
 public function key() { return $this->position; }
 public function next() { ++$this->position; }
 public function rewind() { $this->position=$this->startat; }
 public function valid() { return true; }
}

then your output simplifies to

$iter = new LoopingPropertyIterator( array(
    'outerclass' => array('serial-contain-right','serial-contain-left'),
    'innerclass' => array('text-align2','text-align')
));

...

elseif ( $findpost->ID != $id ) {
    $link = get_permalink($firstpost->ID);
    $title = $findpost->post_title;
    $datetime = mysql2date('M jS, Y', $findpost->post_date).' at '.mysql2date('g:ia', $findpost->post_date);

    $serp_list_li[]=
<<<TEXT
    <div class="{$iter.outerclass}">
        <div class="title">
            <h5><a href="{$link}" title="{$title}">{$title}</a></h5>
        </div>
        <div class="{$iter->innerclass}">{$findpost->excerpt}</div>
        <div class="date">{$date}</div>
        <div class="comments">
            <a href="{$link}#comments"> title="{$title}">
                <b>{$findpost->comment_count} Comments</b>
            </a>
        </div>
    </div>
TEXT;

    $iter->next();
}