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Cosc 4750 Beginning PHP
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Cosc 4750
Beginning PHP
PHP
• PHP => "PHP Hypertext Preprocessor"– Designed for the web
• Cross-platform: Runs on both UNIX and windows (with everything installed correctly)
• PHP is mix of PHP langauge and HTML code• Runs on the Sever-side, specifically on the web server
– Light weight compared to PERL, since it runs inside the web-server itself.
• In many ways PHP is perl, but stripped down with most of the "web" modules already installed.
NOTE
• I'm assuming you know several things:– HTML– SQL– PERL
• I'll use PERL to explain PHP.
• Also, all files are saved with the .php extension on them, instead of .html
Example PHP code
• file: helloworld.php<html> <head> <title>PHP Test</title> </head> <body> <?php echo "<p>Hello World</p>"; ?></body> </html>
• Output to browser<html> <head> <title>PHP Test</title></head> <body> <p>Hello World</p></body> </html>
Comments
• PHP has single line comments like C++
uses the // to start a comment
// This is a comment
$var = 10; //bah… bah…
variables
• like PERL– All variables start with a $
• Unlike PERL– Variables can be typed or typeless– types:
• String String data is always in double quotes• integer, double, array (numeric and hash index), object, and
unknown type• Boolean (value: true or false)
• Displaying variables– echo $variablename;
Using Variables
• Remember this is inside html code!<html><body><? php$CarType = "Ford"$enginesize = "3.0";$car = $cartype . " " . $enginesize;echo $car;?></body></html>
Constants
• Don't use $, instead use a special keyword to create them– define(constantname, value);
– Examples– define("FREEZING", 0);– define(INDEPENCEDAY, "4th of July");– echo "Independence Day is ".
INDEPENDENCEDAY;
Variables and operators
• Same as with PERL– With typed variables
• numeric operators for numeric data types• string operators for string data types
– such as the dot is used for concatenation with strings– can not $str = $str1 + $str2
Getting data from forms
<form action="test.php" method=GET><!– Example input box--><input NAME="var1" Type="text"></form>• OR<form action="test.php" method=POST><input NAME="var1" Type="text"><!– Example input box--></form>• The name comes into the PHP script as a variable<?phpecho $var1;?>NOTE: The name must be the same including case!
Getting Data from forms
• The previous example assumes that your php.ini file has
•register_globals = On
• This is a security risk, so by default it is off• So instead you should use•$var = $_POST['name']; //For post method
•Where name is the name of name listed in the html.
Getting Data from forms Example
• If ($_SERVER['REQUEST_METHOD'] == 'GET') {– $var = $_GET['var'];
• else– $var = $_POST['var'];
• }• New version• $_REQUEST['var']; //both get and post
method.
Avoid errors
• Use the isset function• If (isset($_REQUEST['var'])){
– $var = $_REQUEST['var'];
• Else– $var = “”;
Radio buttons and Check Box
• <input name="choice" type="Checkbox">
• check boxes have the value of on or off
• unless you use the value tag
• <input name="choice" type="Checkbox" value="Computers">
• Same with Radio buttons.
Filling arrays from forms
<form method=get action="test2.php"><input name=arr[] type=text><input name=arr[] type=text><input type=submit></form>• In test2.php• $arr[0] has the value of the first input and
$arr[1] has the value from the second.– Note, filling Arrays won’t work if
register_globals is off.
HTML code input
• To better sanitize your input you can use a the function HTMLSpecialChars(value);
• This convert html codes into text for display.
$string = HTMLSpecialChars("<B>hi</B>");
echo $string;
• Will display <B>hi</b> to the web browser instead of hi.
Control Structures
• If statements– Again like PERL– if (boolean value) { statements }– elseif (boolean value) { statements }– else { statements }
– Boolean operators are the same as in PERL, except you don't have to make any distinctions between string and numerical operators
• < <= == > => !=, AND, &&, OR, ||, ! (NOT)
Control Structures (2)
• switch statement• NOT in perl, just like the C/C++ statementswitch (variable) { case value1: statements; break; case value2: statements; break; default: statements;}• like C/C++ you can leave off the break
Control Structures (3)
• Loopswhile (boolean expression) { statements}
do {statements} while (boolean expression);
Control Structures (4)
• for loops
for (set loop counter; test loop counter; increment/decrement loop counter) {
statements;
}
Arrays structure
• foreach structure– similar to PERL
foreach ($array As $variable) { statements}foreach ($array As $arrIndex => $var) { statements}• second format makes the array index value
available in the loop as well.
More on Arrays
• Initialization (with number index values)– $arr[0] = "value1";– $arr[1] = "value2";– …
• OR allow PHP fill in the numbers– $arr[] = "value1";– $arr[] = "value2";– …
• OR– $arr = array ("value1", "value2", … , "valueX");
• OR (for hashing)– $arr["v1"] = "value1";– $arr["v2"] = "vavlue2";
Hashing array and return values
• Many PHP functions will return an array of data, which can be used as either a hash or a “normal” array.
• $date1 = localtime();– $min = $date1["tm_min"];– $hour = $date1["tm_hour"];– $year = $date1["tm_year"] + 1900;– $mon = $date1["tm_mon"]+1 ;//$mon ++;– $day = $date1["tm_mday"];
More on Arrays (2)
• Iterating through non-sequential arrays and hash arrays.
• list and each functions
while ( list($indexvalue, $element) = each( $array) ) {
echo "The value of element $indexvalue is $element";
}
More on Arrays (3)
• sorting (with index as numbers)sort($array);• sorting hash arrayasort($hasharray);
– NOTE you can use sort on hashes, but the keys (string indices) are replaced with numbers.
• reverse alphabetical order sort• rsort($array) and arsort($hasharray)• ksort($hasharray)
– Sorts based on the keys, instead of the element contents.
More on Arrays (4)
• array_push() and array_pop()– Allows you to use an array as a stack.
• implode and explode functions
• $string = implode("delimiter", $array);– like join statement in PERL
• $arr = explode("delimiter", $string);– like split statement in PERL
functions
function functionname (parameters) { statements; return;• OR return value; //or variable }• Calling the functionfunctionname(parameters);$variable = functionname(parameters);
functions (2)
• pass by valuefunction f1 ($var) { // $var can be altered but won't change the // calling variable}• pass by referencefunction f2 (&$var) { //$var value will now change the calling variable}
functions (3)
• default parameter valuesfunction f3 ($var=2) { //f3 can be called with no parameters // and $var will have the value of 2}• parameter order, since you don't have pass
values to the parametersfunction f4($v1=2, $v2) { statements}f4(12); //$v1 =12, $v2 = 0
functions (4)
• Scope of variables• Variables "declared"
outside of functions are global
• Variables "declared" inside functions are local variables to the function– "declared" is the first
occurrence of the variable.
• creating global variables in functions uses the keyword global
global $variable;• static variablesstatic $variable
– the variable will retain it's value between function calls.
functions (5)
• final notes.
• You can nest functions inside functions– the inner function will cause an error
(redeclaration error) on the second time the outer function is called.
• Recursion– allowed
including files
include("filename");
• Execute a separate PHP script at the point in the code
• include commonly used PHP functions that can be called by this script.
• define variables and/or constants, etc…
• Can be text or html that will be displayed.
File I/O
• similar to PERL file I/O• openfilehandle = fopen("filename", mode);$fp = fopen("data.txt","r"); //read from file data.txt• modes
– "r" read only– "w" for writing only– "a" append, create if doesn't exist.
• close– fclose (filehandle);
File I/O (2)
• reading
• $variable = fread(filehandle,bytes);
$data = fread($fp, 20); // read 20 bytes from the file
• Writing
• fwrite(filehandle, data);
fwrite($fp, "abc");
File I/O (3)
• $c = fgetc($fp) read file one character at a time• feof($fp) returns true if it the end of the file• $arr = file(filename) read in an entire file
– Each line is an element in the $arr
• copy(filename1,filename2) copy f1 to f2• rename(f1, f2) rename f1 to f2• unlink(filename) del filename
– may not work in windows• use system or exec function (see PERL for descriptions)
Directory I/O
• chdir() change directory
• rmdir() delete directory
• mkdir() delete directory
• opendir() open a directory for "reading"
• readdir() read the directory
• closedir() close the directory
PHP database connectivity
• Using mysql as the database to connect to, since it included with our Redhat installation.
• First you need to connect to the database
$link_id = mysql_connect("localhost", "username", "password")
• like mysql command in unix
mysql –u username –p password –h host
PHP database connectivity (2)
• Now we need to select the database to use
mysql_select_db("database", $link_id);• Where $link_id is from the mysql_connect
command
• mysql command
mysql> use database;
PHP database connectivity (3)
• After finishing with the database, you need to close the connection
• mysql_close($link_id);
PHP commands For lab 6
<?php// make the connection$link_id = mysql_connect("localhost", "testacc",
"csteach");//choose the databasemysql_select_db("webacc", $link_id);… //now ready to retreive,modify, or delete datamysql_close($link_id);?>
Accessing the database
• PHP uses one command to send SQL commands to the database (for mysql)– $result = mysql_query("SQL command");
• Another to retrieve results (from say a select), one row of data at a time– $arr = mysql_fetch_row($result);
• //gets first row of data
– $arr = mysql_fetch_row($result); • //gets next row of data
– etc..
With a select
$result = mysql_query("Select * from test");
while($query_data = mysql_fetch_row($result)) {
echo $query_data[0], $query_data[1], $query_data[2], "<BR>";
}
//prints to the browser the contents of the table test, with three rows.
With a select (2)
• Or can use the field names, for better readablity.
$result = mysql_query("Select * from test");
while($query_data = mysql_fetch_array($result)) {
echo $query_data["name"], $query_data["ip"], $query_data["owner"], "<BR>";
}
//prints to the browser the contents of the table test, with three rows.
With an Insert
• $sql = "Insert into test values (‘csteach31’,’129.72.218.41’,’cosc’)";
• mysql_query($sql);– NOTE lack of return value.
• NOTE: inserting "odd" characters such as ' as in I'm won't work.– There is a function to fix it called addslashes
$var = addslashes("I'm"); // result "I\'m"– Removed with the stripslashes() later.
Delete and update
• Use the same php command
$sql = "delete from test where name ='k2' ";
mysql_query($sql);
$sql = "update test set ip='129.72.14.123' where name = 'esig' ";
mysql_query($sql);
results from insert/update/delete
• mysql will tell you how many how many rows were effected by insert, update or delete
• There is a function to get that information from mysql
• $var = mysql_affected_rows($link_id);– $var contains a the number of effected rows.
example• A php script that displays the contains of a the database on a webpage<?php// make the connection$link_id = mysql_connect("localhost", "testacc", "csteach");//choose the databasemysql_select_db("webacc", $link_id);
$result = mysql_query("Select * from test");while($query_data = mysql_fetch_row($result)) { echo $query_data["name"], $query_data["ip"], $queary_data["owner"], “
<BR>"; }
mysql_close($link_id);?>
PHP and e-mail
• Sending e-mail in PHP is very simple– On windows you need set a mailer,
• command: mail( )– It takes 4 arguments
• The intended recipient• subject line• body of the e-mail• Extra headers (optional)
• Example<?phpmail("[email protected]","test", "this is test message");?>
Extra headers field
• Add header like– From:– Reply-To: – Cc:– Bcc:– Others you want to create.
• You need to include the \r\n between the extra headers.
Example
<?php$to = "[email protected]";$subject = "Test message";$body = "This is a test message";$headers = "From:[email protected]\r\nCc:
[email protected]";mail($to,$subject,$body,$headers);?>
Example with html pages
• mail.html<html><body><form method=post action="e-
mail.php">to: <input name=to size=20>From: <input name=from
size=20>subject: <input name=sub
size=30>Message: <textarea name=body
rows=5 cols=30></form>
• e-mail.php<html><body><?php$header = "From: ".$from;mail($to,$sub,$body,$headers);?>You e-mail to $to has been sent.</body></html>
Attachments
• You can also set it up to accept attachments– but we don't have the time to spend on the
details.– It deals with PHP and file uploads, another
setting in the php.ini
additional features built in PHP
• additional features– sessions– use cookies– Persistence of user data between HTTP requests– PHP and XML– generating graphics– Working with the browser client and getting info.– And many functions I skipped over.
• Such as regular expression functions, network functions, etc.
php.ini
• This file contains all the setting that php will use when it executes.– max_execution_time = 30
• Maximum execution time of each script, in seconds
– memory_limit = 8M• Max amount of memory the script can use
– File uploads and max size• file_uploads = On• upload_max_filesize = 2M
• And many more options, make sure you read the comments about each option.
Reference
• Information was found from the web and the book– Beginning PHP4, Choi ..., WROX, 2003– Programming PHP, Lerdorf & Taroe, O’Reilly,
2002– PHP and MYSQL, Williams & Lane, O’Reilly,
2004
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