Using a combination of HTML/PHP, implement a web page where the users can upload a text file, exclusively in .txt format, which contains a string of 400 numbers, such as:
Your code should contain a PHP function that, accepting the string of 400 numbers in input, is able to find the
greatest product of four adjacent numbers in all the four possible directions (up, down, left, right, or diagonally).
? You will need to arrange the numbers in a grid 20×20.
? If the file doesn’t contain 400 numbers or contains some characters in between, it should be discarded
and the application should inform the user that the file is not format correctly.
? You can ignore new lines and white spaces.
? Add a tester function to check the behavior of your PHP function.
? Follow the guidelines discussed and showed in class to avoid losing points.