Usage of the output Defined tag determined by the ThinkPHP Template

The defined tag of the ThinkPHP template engine is usedDetermine whether a constant has been defined.
The defined tag of ThinkPHP is used to determine whether a constant has been defined. Its functionEquivalent to the defined () function in PHP. The usage of the defined label is as follows:

<Present name = "constant"> content to be output </present>

Define a constant in a module operation (such as Index/display) and output the template:

Define ("SITE_NAME", ""); $ this-> display ();

Use the defined tag in the template/Tpl/default/Index/display.html as follows:

<Defined name = "SITE_NAME"> website name: {* SITE_NAME} </defined>

Running this example will output:

Website name: script home

The equivalent php code in this example is as follows:

<? Phpif (defined ("SITE_NAME") {echo 'website name: ', constant ("SITE_NAME") ;}?>

If the judgment is not defined, you can use:

<Notdefined name = "SITE_NAME"> {* SITE_NAME} does not exist. The live definition is not defined. </notdefined>

The preceding two examples are merged as follows:

<Defined name = "SITE_NAME"> website name: {* SITE_NAME} <else/> {* SITE_NAME} No active undefined </defined>