PHP Lecture 2 Xingquan (Hill) Zhu xqzhu@cse.fau

1. PHP Lecture 2Xingquan (Hill) Zhuxqzhu@cse.fau.edu PHP

2. PHP • PHP overview • PHP General Syntactic Characteristics • PHP Output to browser • Primitives, Operations, and Expressions • Control Statement • Array • Function • File access • Cookie • Session • Form process PHP

3. PHP: Files • Deal with any file on the server $fptr = fopen(filename, use_indicator) • Use indicators: • “r” read only, from the beginning • “r+” read and write, from the beginning • “w” write only, from the beginning (also creates the file, if necessary) • “w+” read and write, from the beginning (also creates the file, if necessary) • “a” write only, at the end, if it exists (creates the file, if necessary) • “a+” read and write, read at the beginning, write at the end • “b” binary file: on systems which differentiate between binary and text files $fptr1=fopen(“test1.php”, “w+”); files.php $fptr2=fopen(“test1.php”, “r+”); PHP

4. PHP: Files • fopen could fail • it will return “false” • Use file_exists(filename) to determine whether file exists before trying to open it • Use fopen with “die” • Always use fclose(file_var) to close a file, after your reading/writing Fopen.php PHP

5. PHP: Write to Files • $bytes_written = fwrite(file_var, string) • fwrite returns the number of bytes it wrote • Return “false” on error fwrite.php PHP

6. PHP: Reading Files • Read all or part of the file into a string variable • $str = fread(file_var, #bytes) • To read the whole file, use filesize(file_name) as the second parameter • Read one line from the file • $line = fgets(file_var[, #bytes]) • Reads characters until eoln, eof, or #bytes characters have been read • Read one character from the file • $ch = fgetc(file_var) • Control reading lines or characters with eof detection using feof (TRUE for eof; FALSE otherwise) while(!feof($file_var)) { $ch = fgetc($file_var); } Readingfile.php PHP

7. PHP file access • Read the lines of the file into an array • array file ( string filename) • file() returns the file in an array • Each element of the array corresponds to a line in the file, with the newline still attached. • Upon failure, file() returns FALSE File.phpFiltering.php PHP

8. PHP • PHP overview • PHP General Syntactic Characteristics • PHP Output to browser • Primitives, Operations, and Expressions • Control Statement • Array • Function • File access • Cookie • Session • Form process PHP

9. Building a Shopping Cart • What is a shopping cart • Putting things together and then check out. • A series of scripts that keep track of items a visitor picks to buy from your site until they proceed to the "checkout • Web server is basically stateless • HTTP is stateless • It does not store any information about a web client • Why? • Web server records nothing about the previous actions of a web client • It only knows the current web page the web browser is visiting • How are we going to keep our browser “continuously” connected to the server • So we can feel the we are connected to the server all the time • How are we going to collect information across different web pages • Cookie & Session • Hidden fields of a form • <input type = "hidden" name = “customername" value = “San Jose" /> PHP

10. Cookie • What is a cookie? • An message given to a web browser by a web server, then send back to the server each time the browser requests a page from the server. • What can cookie do for us? • Identify users and store client side information • Authenticate or identify a registered user • No need to sign in again every time they access a website • Where is the cookie located? How does it look like? • C:\Documents and Settings\YourLoginID\Local Settings\Temporary Internet Files • Cookie:hill@google.com • Will browser return all cookies to each server? • No, only those matched domains • Malicious cookies setting • Are cookies dangerous to my computer? • No • Is this a major privacy issue? • You could lose identify information • You have choices of not using any cookie PHP

11. Cookie • Create a cookie with setcookie • setcookie(cookie_name, cookie_value, lifetime) • setcookie("voted", "true", time() + 86400); • setcookie("voted", "true", time() + 60*60*24); • Is “lifetime” important? • Without this value, cookie expires right after you close the current web browser window. • Expired cookies will be deleted without sending back to the server • Cookies must be created before any other HTML is created by the script • Before <html><body>…were sent • How to access the cookie value • Using the $_COOKIE array • setcookie("visits“, $visitcount, time()+3600); • $visitcount = $_COOKIE["visits"]; • Check whether a cookie has been set before • Isset($_COOKIE[“visits”]) Cookie_simple.phpcookie1.php PHP

12. Simple Shopping Cart • How to update cookie value based on your choice? • $_SERVER["PHP_SELF"] • The name of the current script • Using implicit arrays for form values • $_POST • $_GET Simpleupdate.php Updatecookie.phpuppdatecookie1.php PHP

13. Simple Shopping Cart • At checkout page, summarize all the cookie values Checkout.phpcheckout1.php Checkoutmain.php PHP

14. Session Tracking • What is a session • SUN API: Provides a way to identify a user across more than one page request or visit to a Web site and to store information about that user • web applications make use of sessions to remember who you are • A session is available as long as the browser is opened • A session is closed as soon as the browser is closed or you go to another website • Why session? • Some users block cookies for privacy concerns • Are cookie & session same thing? • Cookie • cookies are normally stored in your hard disk • privacy • Session • A session aren't stored in your hard disk • Considered more secure PHP

15. Session tracking • For session tracking, PHP creates and maintains a session tracking id • Create the id with a call to session_start with no parameters • Subsequent calls to session_start retrieves any session variables that were previously registered in the session • To create a session variable • $_SESSION['myVar'] = $myVarValue; • Check session if(isset($_SESSION['myVar'])) { print $_SESSION['myVar']; $_SESSION['myVar']++; } • Example: count number of pages visited Session.phpmain_1.phpmain_2.php PHP

16. Form Process • Action property • Where to send form data • Method property • Post vs get • Each element has unique name • Using implicit arrays for form element access • $_POST • $_GET Simpleform.htmlsimpleform.php PHP

17. A complete Shopping Cart • Client Side: • Set cookie for each page • Collect information across web pages • A summarization form (before user submit the order) • “Submission” -> invoke form processing program • Server Side: • A form processing program • Read form values from $_POST or $_GET array • Process and save values • Confirmation formselection.phpformselection1.php formprocess.php PHP

18. PHP • PHP overview • PHP General Syntactic Characteristics • PHP Output to browser • Primitives, Operations, and Expressions • Control Statement • Array • Function • File access • Cookie • Session • Form process PHP