It’s surprising to me how often I find little functions for tedious tasks, that CodeIgniter already has built in. One of these functions is the alternator() function in the String Helper.

To begin using this function, make sure you have loaded the String Helper with the following code:

$this->load->helper( 'string' );

What the alternator() function does is allow two or more items to be alternated between when iterating through a loop. Example from the CodeIgniter User Guide:

for ( $i = 0; $i < 10; $i++ ) {
    echo alternator( 'string one', 'string two' );
}

There is also no limit to how many parameters you can have:

w...
echo alternator( 'one', 'two', 'three', 'four', 'five' );
...

Put it to Use

What would you ever need that for? Well, what about if you are creating a list of items and every other needs class="alt" attached to it for styling differences? I run into this issue all the time.

This is how I used to do it:

<ul>
    <?php $count = 1; ?>
    <?php foreach ( $list as $item ) : ?>
        <?php ( empty( $count ) ) ? $count = 1 : $count = 0; ?>
        <li <?php echo ( $count == 1 ) ? 'class="alt"' : ''; ?>>
            <?php echo $item; ?>
        </li>
    <?php endforeach; ?>
</ul>

And this is with the alternator() function:

<ul>
    <?php foreach ( $list as $item ) : ?>
        <li <?php echo alternator( 'class="alt"', '' ); ?>>
            <?php echo $item; ?>
        </li>
    <?php endforeach; ?>
</ul>

The alternator() function makes the ability to do this, much easier and cleaner than my original way. Hopefully I’ve helped someone out who had no idea this function was available.