This is a continuation to my post 
PHP Magic Constants.Here I would like to demonstrate a real time example of magic constants.
I am going to write a user function for generating a user-level error/warning/notice message.
function myErrorFunction($error_message,$line,$file)
{
               if($error_message!='')
               {
                       $error_string = "User Error : {$error_message} in
{$file} on line  number {$line}";
                       echo $error_string;
                       die();
               }
}
myErrorFunction('test error message',__LINE__,__FILE__);
Now, you can call this function any where in your
script. It should print the error message as follows.
User Error : test error message in H:\test\ccodlib\test.php on line number 12
In the above function,
•       die() is a portable way of causing the program to crash.
•       __FILE__ is replaced (during compilation) with the name of the file containing the code (as a string).
•       __LINE__ is replaced (during compilation) with the current line number (as an integer constant).
 ------------------
you can also achieve the above functionality by using the built in function "Trigger_error()" provided by PHP. 
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  Posted By  Jansan John  to  
 Techno WeBlog   at  6/08/2007 08:02:00 AM