A count in a loop

Question

Hello i would like do somthing like that:

<?php $count = 0; foreach($a as $v): $count++; ?>
  <?php if ($count%2 == 0): ?>
    ...
  <?php endif; ?>
<?php endforeach; ?>

in twig:

{% for v in a %} 
  {% if ??? is even %}
    ...
  {% endif %}
{% endfor %}

but how can i have a variable evolving with loop ?

vstm · Accepted Answer · 2023-03-27 13:04:35Z

66

Apparently twig defines some loop variables inside the for-loop:

{% for v in a %}
    {% if loop.index0 is even %}
        ...
    {% endif %}
{% endfor %}

edited Mar 27, 2023 at 13:04

answered Dec 26, 2011 at 17:41

vstm

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3 Comments

adriaan Over a year ago

There is also such a thing as {% if loop.index is divisible by(2) %}, which would do the same. twig.symfony.com/doc/2.x/tests/divisibleby.html

Charles Over a year ago

The link in the answer has expired. Use this one instead: twig.symfony.com/doc/3.x/tags/for.html#the-loop-variable

vstm Over a year ago

@Charles hey thank you very much for the message, I have updated my answer accordingly.

Anton Valqk · Accepted Answer · 2015-02-15 14:25:08Z

24

If you use it for styling you can do:

{% for v in a %} 
  <div class="link {{ cycle(['even', 'odd'], loop.index0) }}">
  </div>
{% endfor %}

edited Feb 15, 2015 at 14:25

answered Jun 6, 2012 at 18:47

Anton Valqk

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2 Comments

cmt Over a year ago

Thanks, exactly what I was looking for. However, just a minor fix: It should be cycle(['even', 'odd'], loop.index0) because loop.index0 is used. When you use loop.index0 you are saying you have a "zeroth" row, and zero is an even number. So, with this fix your zeroth row is even, first row is odd, second row is even, etc.

Arvid Over a year ago

Pretty neat solution, especially if you need something different than "even and odd", but for example "1st, 2nd and 3rd". Now, what about performance? Is maybe using {% if loop.index0 is even %} faster than cycling through a list of strings with {{ cycle(['even', 'odd'], loop.index0) }}? Would be interesting to know if there might be any reason to prefer one solution over the other or if it just doesn't matter in the end.

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