Error handling mechanism is too important for the web application to display the error message if the file doesn’t exist .
Error handling mechanism refers to the mechanism that indicates this error to the end-user.
die("File not found");//die used for error handling .
$file = readfile("testfile.txt");
if (condition for check the file if not exist)
die("File not fount");//die used for error handling .
Else file exist read it .
Here you can see that if the file does not exist the statement"File not fount" will print and else(if the file exists in the folder ) read the file.