Determining whether the current browser is a micro-Letter

### to determine if the current browser is a micro-Letter

Determining whether the current browser environment is a micro letter

code show as below:

//判断访问终端是否是微信浏览器
function is_weixin() { 
    if (strpos($_SERVER['HTTP_USER_AGENT'], 'MicroMessenger') !== false) { 
        return true; 
    } return false; 
}