Their description are as below.
1)__LINE__ : This constant prints the current line number of the file.
2)__FILE__ : __FILE__ prints the absolute path of the file. If it is used inside an include, the name of the included file is returned.
3)__DIR__ : It prints the directory name of the file. If used inside an include, the directory of the included file is returned. Note that trailing slash is not there without unix root (/) directory.
4)__FUNCTION__ : It returns the function name. In PHP 5 it is case sensitive but in PHP version 4 its value was always lowercased.
5)__CLASS__ : It returns the class name. In PHP 5 it is case sensitive but in PHP version 4 its value was always lowercased.
6)__METHOD__ : It prints the class method name.
7)__NAMESPACE__ : It returns the name of the current namespace (case-sensitive). This constant is defined in compile-time (Added in PHP 5.3.0).
Code
<html>
<body>
<?php
echo "This example will show about magic constants." ;
echo "<br />";
echo "This is line number: ". __LINE__;
echo "<br />";
echo "This is file name: ". __FILE__;
echo "<br />";
class MyBaseClass
{
function function_a()
{
echo "A function called -" . __CLASS__ . "<br/>";
}
function function_b()
{
echo "B function called -" . get_class($this) . "<br/>";
}
}
class MyDerivedClass extends MyBaseClass
{
function function_a()
{
parent::function_a();
echo "A function called --" . __CLASS__ . "<br/>";
}
function function_b()
{
parent::function_b();
echo "B function called --" . get_class($this) . "<br/>";
echo "This is a function: " .__FUNCTION__ ."<br/ >";
}
}
$object_b = new MyDerivedClass();
$object_b->function_a();
echo "<br/>";
$object_b->function_b();
echo "<br />";
echo "<br />";
?>
</body>
</html>
Output
This example will show about magic constants.
This is line number: 6
This is file name: C:\apache2triad\htdocs\magic_constants.php
A function called -MyBaseClass
A function called --MyDerivedClass
B function called -MyDerivedClass
B function called --MyDerivedClass
This is a function: function_b
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