This article mainly introduces the usage of the ThinkPHP template to determine the output Present tag, which can be used to determine whether the template variable has been assigned a value. if you need it, refer to ThinkPHP.
The present label of the ThinkPHP template is usedDetermine whether the template variable has been assigned a value.
The present tag of the 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.The format is as follows:
Content to be output
Examples:
{$ Username} Hello!
This example is equivalent:
If (isset ($ username) {echo "$ username Hello! ";}
In addition, the notpresent label can be used to judge whether no value is assigned. the usage is as follows:
The username does not exist. the user is not logged on.
You can also merge the preceding two labels:
{$ Username} Hello!
The username does not exist. the user is not logged on.