PHP Rescursive acronym for "PHP: Hypertext Preprocessor".

PHP • Rescursive acronym for "PHP: Hypertext Preprocessor". • It is an open source scripting language that can be embedded into HTML. Php Code is embedded inside HTML code, unlike other scripting languages like Perl which produce WHOLE html codes, PHP code is embeded anywhere inside an HTML code. • JavaScript is client-side processed while PHP is processed on the server side. • When an HTML code with embedded PHP is shown to a client, all the client can see is the final HTML version. They have no way of knowing that some of that code came from PHP.

PHP START AND OPEN TAGS <? ?> <% echo 'ASP -style tags'; %> <?= expression ?> Short cut for <? echo expression ?> <%= $variable %> Short cut for <% echo $variable %> <script language='php'> echo "php code"; </script> The preferred method that is enabled by default in PHP 4 is <?php ?> Others may need further PHP configuration after installing PHP.

PHP is case sensitive just like Java. PHP Autoglobals: $_SERVER is a special reserved PHP variable that contains all web server information. It's known as an Autoglobal. • To display some of the values, do the following:

Printing a variable (Array element) <?php echo $_SERVER["HTTP_USER_AGENT"]; ?> A sample output of this script may be: Mozilla/4.0 (compatible; MSIE 5.01; Windows NT) • $_SERVER is one of many variables automatically made available to you by PHP. You can get a complete list of the auto variables by using: <?php phpinfo(); ?>

PHP interface to the DB • <html> • <body bgColor="#33AACC" Text="#000000"> • <center> • <?php • echo "<h1>$header</h1>"; • $db = mysql_connect("localhost", "db_username", "db_password"); • mysql_select_db("dbname",$db); • $result = mysql_query("SELECT * FROM $tablename",$db); • if ($result == "") { • echo "SORRY, THIS INFORMATION IS CURRENTLY UNAVAILABLE.<br>"; • }

else if ($myrow = mysql_fetch_array($result)) { • echo "<table width=600 cellspacing=0 cellpadding=0 • border=1>\n <tr align=center>"; • /* make header with column names */ • $description = mysql_query("DESCRIBE • $tablename",$db); • echo "<th> Num. </th>"; • $ncols = 0; • while ($colnames = mysql_fetch_array($description)) { • echo "<th> $colnames[0] </th>"; • $ncols = $ncols + 1; • }

echo "</tr>\n"; • $count = 0; • do { • $count = $count + 1; • print "<tr><td>$count</td>"; • for ($i=0; $i < $ncols; $i++) { • print "<td>$myrow[$i]</td>"; • } • print "</tr>\n"; • } while ($myrow = mysql_fetch_array($result)); • } • // mysql_fetch_array may also be indexed as an associative array • // e.g. $myrow[‘id’] works if id is one of the selected attributes. • </table> • </center> • </body> • </html>

FUNCTIONS IN PHP • Examples: <?phpfunction foo($arg) { if ($arg < 10) { echo "$arg is less than 10"; } else { echo "$arg is not less than 0"; }} foo(15); /* Echoes 15 is not less than 10" */ ?>

Use the return statement to have the function return a value e.g. function adder($first, $second) { return $first+$second; } $a = 5; $sum = adder($a,10); /* Call adder */

Reference/value Parameters: An & before the parameter at the function header indicates a reference parameter, otherwise it is a value parameter e.g. $a=1; $c=2; • function test(&$bb) { global $c; // imports (brings in) the externally defined c $bb = $c; $c++; } test($b); echo “$a $b $c”; // displays 1 2 3 – why?

Default Values for Paramaters: • Example: function divide ($num, $den=2) { return $num/$den; } /* $den defaults to 2 if not specified at call time */ echo divide(2); /* echoes 1 */

Some useful pre-defined functions: gettype($var) - Get the type of a variable settype($var, type) - Set a variable to a certain type e.g. settype($myvar, "integer"); isset($var) - Determine whether a variable is set i.e. has a value unset($var) - Unset a given variable, destroys the specified variable and returns true isset example: <?phpif (isset($var)) { echo "Your variable is set";} else { echo "Your variable was not set";} ?>

Scope of variables: Variables declared or used in a function are local to that function. For a function to access a variable outside of the function block, it must use the global keyword to import the variable. Example: <?php $tax = 1.06; $state = 'MI'; $weight = 5; function total(&$total, $shipping = 1.33) { global $tax, $state, $weight; //import global variables if ($state == 'MI') { $total = $tax * $total + ($shipping * $weight); } else { $total = $shipping * $weight; } } $total = 1000; total($total); printf( “Total with shipping and tax (if applicable) is: <b>$%.2f</b>", $total); ?> static $var=0; within a function forces $var to remain static over calls to the function.

Functions may be placed in a file and included in the scripts that may need them. In PHP4, if you have a return statement at the end of the include file, the returned value may be assigned to a variable at the include statement Example: <?php/* foo.inc file. */function f1() { echo “hello world”; } $x = 20; return time(); ?> Then you could write the following in script.php: <?php$y = include('foo.inc'); // include ‘foo.inc’ works too // more PHP code my be added before or after the include. ?>

setcookie -- Send a cookie boolean setcookie ( string name [, string value [, int expire [, string path [, string domain [, int secure]]]]]) setcookie() defines a cookie to be sent along with the rest of the header information. Cookies must be sent before any other headers are sent (this is a restriction of cookies, not PHP). This requires you to place calls to this function before any <html> or <head> tags. If headers exist prior to calling this function, setcookie() will fail and return FALSE. If setcookie() successfully runs, it will return TRUE This does not mean the user accepted the cookie or not. • All the arguments except the name argument are optional. If only the name argument is present, the cookie by that name will be deleted from the remote client. You may also replace any argument with an empty string ("") in order to skip that argument. The expire and secure arguments are integers and cannot be skipped with an empty string. Use a zero (0) instead.

Expire=date value The expire argument is a regular Unix time integer as returned by the time() or mktime() functions. • The date string is formatted as: Wdy, DD-Mon-YYYY HH:MM:SS GMT. For example, Sunday, 03-Nov-2002 00:00:00 GMT

domain=DOMAIN_NAME • When searching the cookie list for valid cookies, a comparison of the domain attributes of the setcookie function is made with the Internet domain name of the host (server) setting the cookie. If there is a tail match, then the cookie will go through path matching to see if it should be sent. "Tail matching" means that domain attribute is matched against the tail of the fully qualified domain name of the host. A domain attribute of “emich.edu" would match host names “my.emich.edu”. • The default value of domain is the host name of the server which generated the cookie response.

path=PATH • The path attribute is used to specify the subset of URLs in a domain for which the cookie is valid. If a cookie has already passed domain matching, then the pathname component of the URL is compared with the path attribute, and if there is a match, the cookie is considered valid and is sent along with the URL request. The path "/foo" would match "/foo/bar" and "/foo/bar.html". The path "/" is the most general path. • If the path is not specified, it as assumed to be the same path as the document being described by the header which contains the cookie. • The secure indicates that the cookie should only be transmitted over a secure HTTPS connection.

Once the cookies have been set, they can be accessed on the next page load with the $_COOKIE or $HTTP_COOKIE_VARS arrays. Common Pitfalls: • Cookies will not become visible until the next loading of any page that the cookie is intended for. To test if a cookie was successfully set, check for the cookie on a next loading page before the cookie expires. Expire time is set via the expire parameter. • Cookies must be deleted with the same parameters as they were set with. • Cookies names can be set as array names and will be available to your PHP scripts as arrays but seperate cookies are stored on the users system..

Example 1. setcookie ("TestCookie", $value); setcookie ("TestCookie", $value,time()+3600); /* expire in 1 hour */ setcookie ("TestCookie", $value,time()+3600, "/~ikeji/", “db1.acad.emich.edu", 0);

DELETING COOKIE When deleting a cookie you should assure that the expiration date is in the past, to trigger the removal mechanism in your browser. Examples follow how to delete cookies sent in previous example: setcookie ("TestCookie", "", time() - 3600); setcookie ("TestCookie", "", time() - 3600, "/~ikeji/", “db1.acad.emich.edu", 1); Note that the value portion of the cookie will automatically be urlencoded when you send the cookie, and when it is received, it is automatically decoded and assigned to a variable by the same name as the cookie name. To see the contents of our test cookie in a script, use echo $_COOKIE["TestCookie"];

You may also set array cookies by using array notation in the cookie name. This has the effect of setting as many cookies as you have array elements, but when the cookie is received by your script, the values are all placed in an array with the cookie's name: setcookie ("cookie[three]", "cookiethree"); setcookie ("cookie[two]", "cookietwo"); setcookie ("cookie[one]", "cookieone"); if (isset ($_COOKIE[‘cookie’])) { $arr = $_COOKIE[‘cookie’]; while (list ($name, $value) = each ($arr)) { echo "$name == $value<br>\n"; } }

PHP/RADIO BOX EXAMPLE <html><body> <form action=“ans.php" method="post"> What is your name?: <input type=‘text’ name=‘nm’ size=30><br> What is 1+1? <input type="radio" name="choice" value=“1" checked>1 <input type="radio" name="choice" value=“2">2<input type="radio" name="choice" value=“3">3<input type="submit" value="Submit"> </form> </body></html>

On the ans.php, you may access the ans by using <?php echo $_POST[‘nm’]; if ($_POST[‘choice’] == “2”) { echo “correct”; } else { echo “sorry, wrong answer”; } ?>

PHP/CHECK BOXES EXAMPLE <form action=“ans.php"> // default is get method<input name=“choices[]" type="checkbox" value=“A">A<input name=“choices[]" type="checkbox" value=“B">B<input name=“choices[]" type="checkbox" value="C">C<input name=“choices[]" type="checkbox" value="D">D<input type="submit" name="submit" value="Submit"> </form> PHP Code to process it <?php$items = $_GET[‘choices’];for ($i=0; $i<count($items); $i++){ echo "$items[$i]”;} ?>

PHP/SELECT BOXES EXAMPLE • To pass multiple values, as in a "Multiple Select Box", put [] after the variable name, like choices[]. • <SELECT NAME=“choices[]" MULTIPLE SIZE=“3"> <OPTION VALUE="1">One</OPTION> <OPTION VALUE="2">Two</OPTION> <OPTION VALUE=“3">Three</OPTION> <OPTION VALUE=“4">Four</OPTION> <OPTION VALUE=“5">Five</OPTION></SELECT>

On the receiving page, you simply do a count() on choices, and iterate through the list of values that was selected just like in the checkbox example. <?php$items=$_GET[‘choices’]; for ($i=0; $i<count($items); $i++) { echo $items[$i];} ?>

PHP/FILE UPLOAD EXAMPLE <form action="file-upload.php" method="post" enctype="multipart/form-data"> Send these files:<br> <input name="userfile[]" type="file"><br> <input name="userfile[]" type="file"><br> <input type="submit" value="Send files"> </form>

When the above form is submitted, the arrays $_FILES['userfile'], $_FILES['userfile']['name'], and $_FILES['userfile']['size'] will be initialized. For instance, assume that the filenames /home/test/one.html and /home/test/two.out are submitted. In this case, $_FILES['userfile']['name'][0] would contain the value one.html, and $_FILES['userfile']['name'][1] would contain the value two.out. $_FILES['userfile'][‘tmp_name'][0], $_FILES[‘userfile’][‘tmp_name’][1] will contain the temporary local names of the files on the server. Use these names to access the files on the local server. Similarly, $_FILES['userfile']['size'][0] and $_FILES['userfile']['type'][0] are also set.

fgets • (PHP 3, PHP 4 ) • fgets -- Gets line from file pointer • Description • string fgets ( int fp [, int length])Returns a string of up to length - 1 bytes read from the file pointed to by fp. Reading ends when length - 1 bytes have been read, on a newline (which is included in the return value), or on EOF (whichever comes first). If no length is specified, the length defaults to 1k, or 1024 bytes. • If an error occurs, returns FALSE.

FILE I/O EXAMPLE <?php $FILE = fopen(“in.dat","r"); // for reading only $NEWFILE = open(“out.dat","w");// open for writing only // continously read in from data.txtwhile ($BUFFER = fgets($FILE,4096)) { fputs($NEWFILE,$BUFFER); //write to out.dat} fclose($FILE); // close in.datfclose($NEWFILE); // close out.dat ?>

RELATED FILE UPLOAD FUNCTIONS bool move_uploaded_file ( string filename, string destination)This function checks to ensure that the file designated by filename is a valid upload file (meaning that it was uploaded via PHP's HTTP POST upload mechanism). If the file is valid, it will be moved to the filename given by destination. • If filename is not a valid upload file, then no action will occur, and move_uploaded_file() will return FALSE.

PHP Rescursive acronym for "PHP: Hypertext Preprocessor".