ThinkPHP template judgment output Present tag usage detailed explanation_PHP tutorial

The present tag of ThinkPHP template is used to determine whether the template variable has been assigned a value .

The present tag of ThinkPHP template engine is used to determine whether the template variable has been assigned a value. Its function is equivalent to the isset() function behavior in PHP , and the format is as follows:

<present name="变量名">要输出的内容</present>

Usage examples are as follows:

<present name="username">{$username} 你好！</present>

This example is equivalent to:

if(isset($username)){
  echo "$username 你好！";
}

In addition, the notpresent tag can be used to judge that there is no assignment. The usage is as follows:

<notpresent name="username">username不存在活未登录</notpresent>

You can also combine the above two tags into:

<present name="username">{$username} 你好！<else/>username不存在活未登录</present>