twig - 循环计数

Question

您好我想做这样的事情:

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

在 Twig 上:

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

但是我怎样才能让变量随着loop演变呢？

Answer 1

显然，twig在for循环内定义了一些loop variables:

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