{% if "bc" in "abcdef" %}
  This appears since "bc" is a substring of "abcdef"
{% endif %}
 
{% if "hello" in greetings %}
  If greetings is a list or set, one element of which is the string
  "hello", this will appear.
{% endif %}
 
{% if user in users %}
  If users is a QuerySet, this will appear if user is an
  instance that belongs to the QuerySet.
{% endif %}
 

{if strpos($product.category_id, $category.id) !== false}
    <li><a href="/product/{$product.id}/">{$product.title}</a></li>
{/if}
 

{if strpos($product.category_id, $category.id) !== false }
    <li><a href="/product/{$product.id}/">{$product.title}</a></li>
{/if}

<?php if (strpos ( $this->_tpl_vars['product']['category_id'] , $this->_tpl_vars['category']['id'] ) !== false): ?>
    <li><a href="/product/<?php echo $this->_tpl_vars['product']['id']; ?>/"><?php echo $this->_tpl_vars['product']['title']; ?></a></li>
<?php endif; ?>
 

{if strpos($product.category_id, strval($category.id)) !== false}
    <li><a href="/product/{$product.id}/">{$product.title}</a></li>
{/if}

$my_string_var = (string) 100500;

{if $value|strpos:"foo" !== false}