thinkphp template judgment output present label usage _php Example

The present label for the thinkphp template is used to determine whether the template variable has been assigned a value .

The thinkphp template engine's present tag is used to determine whether a template variable has been assigned a function equivalent to the isset () function in PHP, in the following format:

<present name= "variable name" > What to Output </present>

Examples of usage are as follows:

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

This example is equivalent to:

if (Isset ($username)) {
  echo $username Hello! ";
}

In addition, a notpresent label is used to determine that no value is assigned, as follows:

<notpresent name= "username" >username does not exist live not logged in </notpresent>

You can also combine the above two tags into:

<present name= "username" >{$username} Hello! <else/>username does not exist live not logged in </present>