$key要查找的字符，
$strArr数组，
{if in_array($key,$strArr)}
输出
{/if}
模板里判断的，两个变量：
{$key}
{$str}
其中
$key=”1″;
$str=”,1,3,5,”;
$strArr = explode(“,”, $str);
在模板中使用格式：
{if in_array($key, $strArr)}Ok{else}Not in!{/if}
应用举例：
<input name="purchase_category[]" type="checkbox" value="tea"
{if in_array("tea", explode(",",$distributor.purchase_category))}checked="checked"{/if}
/>茶叶
<input name="purchase_category[]" type="checkbox" value="tea_tool" {if in_array("tea_tool", explode(",",$distributor.purchase_category))}checked="checked"{/if} />茶具
<input name="purchase_category[]" type="checkbox" value="tea_food" {if in_array("tea_food", explode(",",$distributor.purchase_category))}checked="checked"{/if} />茶食品
<input name="purchase_category[]" type="checkbox" value="tea_use" {if in_array("tea_use", explode(",",$distributor.purchase_category))}checked="checked"{/if} />茶日用品
<input name="purchase_category[]" type="checkbox" value="tea_pack" {if in_array("tea_pack", explode(",",$distributor.purchase_category))}checked="checked"{/if}/>茶包装
<input name="purchase_category[]" type="checkbox" value="other" {if in_array("other", explode(",",$distributor.purchase_category))}checked="checked"{/if} />其他
