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Basic php. Php. Official site: www.php.net PhP manual: http://www.php.net/manual/en/index.php Useful package (Apache, MySql,PhP): http://www.easyphp.org/. Where ?. Ssh into cobweb.seas.gwu.edu and put your php files. Make sure they are readable by everyone.
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Php • Official site: www.php.net • PhP manual: http://www.php.net/manual/en/index.php • Useful package (Apache, MySql,PhP): http://www.easyphp.org/
Where ? • Ssh into cobweb.seas.gwu.edu and put your php files. Make sure they are readable by everyone. • Access them via http://www.student.seas.gwu.edu/~yourusername/filename.php
What is PhP • “PHP is a widely-used general-purpose scripting language that is especially suited for Web development and can be embedded into HTML” (www.php.net) • Server scripting language (Javascript is a client side scripting language) • If you know C, you will learn PhP in no time.
Hello World! • Index.php: <html> <head> <title>PHP Test</title> </head> <body> <?php echo '<p>Hello World</p>'; ?></body></html> • Output <html>: <head> <title>PHP Test</title> </head> <body> <p>Hello World</p> </body> </html>
Basics • Use echo for printing • Variables start with $ sign • Do not have to explicitly assign them a type (like int, array, etc.) • If $x=3 and $a=’x’, echo $$a will display 3, because $$a=$($a)=$x=3; • . (dot) concatenates 2 strings. Ex $a=”Hello”;$b=”World”; echo $a.” ”.$b; displays ”Hello World”
Accesing databases from PhP <html> <head> <title>PHP Test</title> </head> <body> <?php $link=mysql_connect("localhost",“username",“password") or die("Error connecting to the database server:".mysql_error()."<br>\n"); mysql_select_db(“username") or die("Error selecting the database:".mysql_error()."<br>\n"); ?> <?php $sql = "SELECT fname, sid FROM students;"; $result=mysql_query($sql); while(list($name,$id) = mysql_fetch_array($result)) { echo "<p>".$name." ".$id; } ?> </body> </html>
Arrays • A mapping between keys and values. Example <?php$arr = array("foo" => "bar", 12 => true);echo $arr["foo"]; // barecho $arr[12]; // 1 foreach ($arr as $key => $value) { echo “key=”.$key; echo “ value=”,$value.”<BR>”; } ?>
Get and Post • $_GET[’variablename’] – the variable is appended to the http address, and is transmited in the same stream. Ex: http://www.somesite.com/index.php?a=1&b=’x’. Easy to bookmark • $_POST[’variablename’] – a new stream is created, and all the post variables are transmited in this stresm. The http address is clean (no bookmarks)
Get variables from forms Action.php <HTML> <BODY> <?php echo "Your name is ".$_POST["name"]." and you are ".$_POST["age"]." years old";?> </BODY> </HTML> getName.html <HTML> <BODY> <form action="action.php" method="post"> <p>Your name: <input type="text" name="name" /></p> <p>Your age: <input type="text" name="age" /></p> <p><input type="submit" value="Submit"/></p> </form> </BODY> </HTML> Exercise: try it with “get” now.
Some usefull global variables • $_SERVER[’PHP_SELF’]- The filename of the currently executing script, relative to the document root. For instance, $_SERVER['PHP_SELF'] in a script at the address http://example.com/test.php/foo.bar would be /test.php/foo.bar. • $_SERVER['SERVER_NAME']- The name of the server host under which the current script is executing. If the script is running on a virtual host, this will be the value defined for that virtual host. • $_SESSION -An associative array containing session variables available to the current script. • __LINE__The current line number of the file. • __FILE__The full path and filename of the file. If used inside an include, the name of the included file is returned.
Session • HTTP is stateless • Simulates a statefull connection. Maintains records on the server side until the browser is closed. • session_start(); • $_SESSION[‘foo’]=‘bar’; • $_SESSION[‘a’][‘b’]=‘c’; • Allows to build a ”shoping cart”;
Includes • header.php • <html> • <head> • <title>PHP Test</title> • </head> • <body> • <TABLE width="800" cellpadding="4" cellspacing="0" align="center" border="0"> • <TR> • <TD width='100%'> • footer.php • </TD> • </TR> • </TABLE> • </body> • </html> • index.php • <?php • include ”header.php”; • echo ”hello world”; • include ”footer.php” • ?>
