custom error die

The code is checking if a file called 'test.txt' exists, using the file_exists() function. If the file does not exist, the script calls the die() function and prints the string 'Error: this file does not exist' and exits the script. If the file does exist, the script continues to execute the code that follows this block.

The die() function is similar to the exit() function in that it terminates the execution of the script. However, die() also sends a message to the browser. The message parameter is optional, but when provided it is used as the error message. In this case, the message 'Error: this file does not exist' is displayed to the browser.

<?php
// if file test.txt does not exist, it will throw an error by using die function
if (!file_exists('test.txt')) {
    die('Error: this file does not exist');
}