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PHP 1-2
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 1-3
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 1-4
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 1-5
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 1-6
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 1-7
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.php Filtering.php
PHP 1-8
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 1-9
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 1-10
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:[email protected] 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 1-11
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.php cookie1.php
PHP 1-12
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.php uppdatecookie1.php
PHP 1-13
Simple Shopping Cart
At checkout page, summarize all the cookie values
Checkout.php checkout1.php
Checkoutmain.php
PHP 1-14
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 1-15
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.php main_1.php main_2.php
PHP 1-16
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.html simpleform.php
PHP 1-17
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.php formselection1.phpformprocess.php
PHP 1-18
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
