The following code shows how to inspect the URL that the user used to access our application, and extract some information from there.
Save this content as your index.php:
<?php $looking = isset($_GET['title']) || isset($_GET['author']); ?> <!DOCTYPE html> <html> <body> <p>You lookin'? <?php echo (int) $looking; ?></p> <p>The book you are looking for is</p> <ul> <li><b>Title</b>: <?php echo $_GET['title']; ?></li> <li><b>Author</b>: <?php echo $_GET['author']; ?></li> </ul> </body> </html>
Now access the link, http://localhost:8000/?author=Jason&title=my book
For each request, PHP stores all the parameters that come from the query string in an array called $_GET.
Each key of the array is the name of the parameter, and its associated value is the value of the parameter.
So $_GET contains two entries: $_GET['author'] contains Jason and $_GET['title'] has the value my book.
Here, we assign a Boolean value to the variable $looking.
If either $_GET['title'] or $_GET['author'] exists, that variable will be true, otherwise false.
We cast a Boolean to an integer means that the result will be 1 if the Boolean is true or 0 if the Boolean is false.
As $looking is true since $_GET contains valid keys, the page shows a "1".
If we try to access the same page without sending any information, as in http://localhost:8000, the browser will say Are you looking for a book? 0.