增量聲明整型變量

Question

我嘗試做的斑馬條紋：

{% set counter = 0 %} 
{% for entity in entities %} 
    <tr class="{{ cycle(['odd', 'even'], counter) }}"> 
    {% counter++ %} 

，但我得到的錯誤：

Unexpected tag name "counter" (expecting closing tag for the "for" tag defined near line 11)

可能有人給我解決？

[編輯]

我壞的解決方案是很容易的：

{% set counter = counter + 1 %}