Server-side Programming in PHP. History of PHP PHP originally stood for “Personal Home Page” It started out, in 1994, as a simple preprocessor of HTML.

Server-side Programming in PHP

History of PHP PHP originally stood for “Personal Home Page” It started out, in 1994, as a simple preprocessor of HTML files –built by Rasmus Lerdorf (born in Greenland, grew up in Denmark and Canada, graduated from U of Waterloo in 1993, now prominent member of Open Source movement) –original purpose was to log people who viewed his on-line resume Since then, has been developed by a growing community of open source developers Name now supposed to stand for “Hypertext Pre- Processor”

PHP history (contd.) Initially, PHP comprised a simple parser plus a library of C functions The parser would scan a HTML file looking for instances of a new non-standard tag and replace the contents of these tag instances with the result of executing some functions in the C library As a result, much PHP syntax looks like C Other parts of it, however, have a Perl flavour – but, of course, Perl also borrows C syntax

Enabling PHP in HTTP servers PHP is available on many servers today, in Windows and all types of Unix environments It is supported by Apache, AOLServer, Roxen and others Servers can be configured to enable PHP in different ways We will assume that the httpd recognizes a file who name has the suffix.php as a PHP file

A first PHP file PHP Test Hello World "; ?>

How PHP files are processed The httpd demon simply copies regular HTML content in the.php file to the message body that will be sent to a client which requests the.php file The new non-standard tag is of the form The text inside the tag is PHP code Hello World "; ?> The httpd demon executes this PHP code and copies the output text, generated by this PHP code, to the message body that will be sent to the client Thus, from the above, the client would see only Hello World

Suppose we request this file cosmos.ucc.ie> telnet csweb.ucc.ie 80 Trying 143.239.75.219... Connected to csweb.ucc.ie. Escape character is '^]'. GET /j.bowen/cs3314/demos/file1.php

Here is the response PHP Test Hello World Connection closed by foreign host. Cosmos.ucc.ie> /staff/jabowen>

PHP files are not special PHP files do not have to be executable They can be regarded as simply HTML files with some new tags

PHP tags In the example just seen, the PHP tag was This is the best PHP tag to use – it is the one which works best if we are also using XML, because it avoids conflicts with XML Processing Instructions However, you may occassionally see the following tags being used in other people’s PHP code: …

Variables in PHP Variables in PHP are denoted by a dollar sign followed by the name of the variable. A variable name is case-sensitive. A valid variable name starts with a letter or underscore, followed by any number of letters, numbers, or underscores.

Example Usage of Variables Greetings Greetings <?php $person = "Tom"; $Person = "Dick"; echo "Hello $person and $Person"; ?>

Automatic variables in PHP One of the main benefits of PHP is that it provides lots of variables automatically Consider, for example, the.php file on the next slide It produces the output on the following two slides when viewed by MSIE 6.0 and Netscape 2.0

Example usage of automatic PHP variable Your browser Your Browser You are using to view this page.

A warning about pre-defined variables The way in which PHP supports pre-defined variables has changed recently –The way shown on the previous slide is the newer way –But there is also an older way This will be discussed in a future lecture

Data Types in PHP PHP supports eight primitive data types There are four scalar types –boolean –integer –floating-point number –string There are two structured types –array –object There are two special data types –resource –NULL The programmer does not specify the type of a variable –a variable’s type is determined from the context of its usage

Booleans The boolean data type admits two values –true (case-insensitive) –false (case-insensitive) Example usage $itIsRainingToday = true; $thePrinterIsBusy = True; $theQueueIsEmpty = FALSE;

Integers Integers can be specified in decimal, hexadecimal or octal notation, optionally preceded by a sign –In octal notation, the number must have a leading 0 –In hexadecimal notation, the number must have a leading 0x. Examples $a = 1234; # decimal number $a = -123; # a negative number $a = 0123; # octal number (equivalent to 83 decimal) $a = 0x1B; # hexadecimal number (equivalent to 27 decimal) The maximum size of an integer is platform- dependent, but usually it’s 32 bits signed – about 2,000,000,000 PHP does not support unsigned integers.

Floating Point Numbers These can be specified using any of these forms : $a = 1.234; $a = 1.2e3; $a = 7E-10; The maximum size of a float is platform- dependent, although most support a maximum of about 1.8e308 with a precision of roughly 14 decimal digits

Strings A string literal can be specified in three different ways : – single quoted – double quoted – heredoc syntax

Single-quoted Strings In single-quoted strings, single-quotes and backslashes must be escaped with a preceding backslash Example usage echo 'this is a simple string'; echo 'You can embed newlines in strings, just like this.'; echo ‘Douglas MacArthur said "I\'ll be back” when leaving the Phillipines'; echo 'Are you sure you want to delete C:\\*.*?';

Double-quoted Strings In double-quoted strings, –variables are interpreted to their values, and –various characters can be escaped \n linefeed \r carriage return \t horizontal tab \\ backslash \$ dollar sign \” double quote \[0-7]{1,3} a character in octal notation \x[0-9A-Fa-f]{1,2} a character in hexadecimal notation

Heredoc Strings Heredoc strings are like double-quoted strings without the double quotes A heredoc string is delimited as follows –The string is preceded by <<< followed by a label –The string followed by a 2 nd occurrence of the same label Example usage $str = <<<EOD Example of string spanning multiple lines using heredoc syntax. EOD;

String-manipulation functions PHP provides huge range of string- manipulation functions: –addcslashes -- Quote string with slashes in a C style –addslashes -- Quote string with slashes –bin2hex -- Convert binary data into hexadecimal representation –chop -- Alias of rtrim() –chr -- Return a specific character –chunk_split -- Split a string into smaller chunks –convert_cyr_string -- Convert from one Cyrillic character set to another –count_chars -- Return information about characters used in a string –crc32 -- Calculates the crc32 polynomial of a string –crypt -- One-way string encryption (hashing) –echo -- Output one or more strings –explode -- Split a string by string –get_html_translation_table -- Returns the translation table used by htmlspecialchars() and htmlentities()

–get_meta_tags -- Extracts all meta tag content attributes from a file and returns an array –hebrev -- Convert logical Hebrew text to visual text –hebrevc -- Convert logical Hebrew text to visual text with newline conversion –htmlentities -- Convert all applicable characters to HTML entities –htmlspecialchars -- Convert special characters to HTML entities –implode -- Join array elements with a string –join -- Join array elements with a string –levenshtein -- Calculate Levenshtein distance between two strings –localeconv -- Get numeric formatting information –ltrim -- Strip whitespace from the beginning of a string –md5 -- Calculate the md5 hash of a string –md5_file -- Calculates the md5 hash of a given filename –metaphone -- Calculate the metaphone key of a string –nl2br -- Inserts HTML line breaks before all newlines in a string –ord -- Return ASCII value of character –parse_str -- Parses the string into variables –print -- Output a string –printf -- Output a formatted string

–quoted_printable_decode -- Convert a quoted-printable string to an 8 bit string –quotemeta -- Quote meta characters –str_rot13 -- Perform the rot13 transform on a string –rtrim -- Strip whitespace from the end of a string –sscanf -- Parses input from a string according to a format –setlocale -- Set locale information –similar_text -- Calculate the similarity between two strings –soundex -- Calculate the soundex key of a string –sprintf -- Return a formatted string –strncasecmp -- Binary safe case-insensitive string comparison of the first n characters –strcasecmp -- Binary safe case-insensitive string comparison –strchr -- Find the first occurrence of a character –strcmp -- Binary safe string comparison –strcoll -- Locale based string comparison –strcspn -- Find length of initial segment not matching mask –strip_tags -- Strip HTML and PHP tags from a string –stripcslashes -- Un-quote string quoted with addcslashes() –stripslashes -- Un-quote string quoted with addslashes()

–stristr -- Case-insensitive strstr() –strlen -- Get string length –strnatcmp -- String comparisons using a "natural order" algorithm –strnatcasecmp -- Case insensitive string comparisons using a "natural order" algorithm –strncmp -- Binary safe string comparison of the first n characters –str_pad -- Pad a string to a certain length with another string –strpos -- Find position of first occurrence of a string –strrchr -- Find the last occurrence of a character in a string –str_repeat -- Repeat a string –strrev -- Reverse a string –strrpos -- Find position of last occurrence of a char in a string –strspn -- Find length of initial segment matching mask –strstr -- Find first occurrence of a string –strtok -- Tokenize string –strtolower -- Make a string lowercase –strtoupper -- Make a string uppercase –str_replace -- Replace all occurrences of the search string with the replacement string

–strtr -- Translate certain characters –substr -- Return part of a string –substr_count -- Count the number of substring occurrences –substr_replace -- Replace text within a portion of a string –trim -- Strip whitespace from the beginning and end of a string –ucfirst -- Make a string's first character uppercase –ucwords -- Uppercase the first character of each word in a string –vprintf -- Output a formatted string –vsprintf -- Return a formatted string –wordwrap -- Wraps a string to a given number of characters using a string break character. –nl_langinfo -- Query language and locale information

Arrays An array in PHP is a structure which maps keys to values The keys can specified explicitly or they can be omitted If keys are omited, integers starting with 0 are keys The value mapped to a key can, itself, be an array, so we can have nested arrays

Specifying an array A special function is used to specify arrays array( ) Format of Usage array( [key =>] value, … ) A key is either a string or a non-negative integer A value can be anything

Specifying an array (contd.) Format of array specification array( [key =>] value,... ) Here is a hash array: $mothers = array (“tom"=>“mary", “mick"=>“ann", “bill"=>“orla"); Implicit indices are integers, starting at 0 –Here is an ordinary array (indexed by integers, starting at 0): $places = array (“Cork”, “Dublin”, “Galway”);

Specifying an array (contd.) If an explicit integer index is followed by implicit indices, they follow on from the highest previous index – Here is an array indexed by integers 1, 2, 3 $places = array (1 => “Cork”, “Dublin”, “Galway”); –Here is an array indexed by integers 1, 5, 6 $places = array (5=> “Cork”, 1 => “Dublin”, “Galway”);

Specifying an array (contd.) A two-dimensional hash array $parents = array ( “tom” => array (“father” => “bill”, “mother”=> “mary”), “dave” => array(“father” => “tom”, “mother” => orla”) ); A two-dimensional ordinary array $heights = array ( array (10,20), array(100,200) );

Array Example 1 Array Demo Array Demo <?php $capital = array ('France'=>'Paris','Ireland'=>'Dublin'); echo 'The capital of Ireland is '; echo $capital['Ireland']; ?>

Array Example 2 Array Demo Array Demo <?php $capital = array ('France'=>'Paris', ‘Ireland'=>'Dublin'); echo "The various capitals are\n "; foreach ($capital as $city) { echo " $city "; }; echo " " ?>

Array Example 3 Array Demo Array Demo <?php $capital = array ('France'=>'Paris', 'Ireland'=>'Dublin'); echo "The various capitals are\n "; foreach ($capital as $country => $city) { echo " The capital of $country is $city "; }; echo " " ?>

Array Example 4 Details about Fred Details about Fred <?php $ages = array ("Fred" => 2, "Tom"=> 45); $parents = array ("Fred" => array("father" => "Tom", "mother"=>"Mary")); print " Fred's age is "; print $ages["Fred"]; print ". "; print " His father is "; print $parents["Fred"]["father"]; print ". "; ?>

Array-manupulation functions PHP provides a huge set of array-manipulation functions array -- Create an array array_change_key_case -- Returns an array with all string keys lowercased or uppercased array_chunk -- Split an array into chunks array_count_values -- Counts all the values of an array array_diff -- Computes the difference of arrays array_filter -- Filters elements of an array using a callback function array_flip -- Flip all the values of an array array_fill -- Fill an array with values array_intersect -- Computes the intersection of arrays array_key_exists -- Checks if the given key or index exists in the array array_keys -- Return all the keys of an array array_map -- Applies the callback to the elements of the given arrays array_merge -- Merge two or more arrays array_merge_recursive -- Merge two or more arrays recursively array_multisort -- Sort multiple or multi-dimensional arrays array_pad -- Pad array to the specified length with a value

array_pop -- Pop the element off the end of array array_push -- Push one or more elements onto the end of array array_rand -- Pick one or more random entries out of an array array_reverse -- Return an array with elements in reverse order array_reduce -- Iteratively reduce the array to a single value using a callback function array_shift -- Shift an element off the beginning of array array_slice -- Extract a slice of the array array_splice -- Remove a portion of the array and replace it with something else array_sum -- Calculate the sum of values in an array. array_unique -- Removes duplicate values from an array array_unshift -- Prepend one or more elements to the beginning of array array_values -- Return all the values of an array array_walk -- Apply a user function to every member of an array arsort -- Sort an array in reverse order and maintain index association asort -- Sort an array and maintain index association compact -- Create array containing variables and their values count -- Count elements in a variable current -- Return the current element in an array

each -- Return the current key and value pair from an array and advance the array cursor end -- Set the internal pointer of an array to its last element extract -- Import variables into the current symbol table from an array in_array -- Return TRUE if a value exists in an array array_search -- Searches the array for a given value and returns the corresponding key if successful key -- Fetch a key from an associative array krsort -- Sort an array by key in reverse order ksort -- Sort an array by key list -- Assign variables as if they were an array natsort -- Sort an array using a "natural order" algorithm natcasesort -- Sort an array using a case insensitive "natural order" algorithm next -- Advance the internal array pointer of an array pos -- Get the current element from an array prev -- Rewind the internal array pointer range -- Create an array containing a range of elements reset -- Set the internal pointer of an array to its first element

rsort -- Sort an array in reverse order shuffle -- Shuffle an array sizeof -- Get the number of elements in variable sort -- Sort an array uasort -- Sort an array with a user-defined comparison function and maintain index association uksort -- Sort an array by keys using a user-defined comparison function usort -- Sort an array by values using a user-defined comparison function

Objects PHP supports object-oriented programming The subject is too big to cover here But here’s an example <?php class thingAMeBob { function say_hello() { echo “Hello, World!"; } } $thing1 = new thingAMeBob; $thing1->say_hello(); ?>

Resources This data type is used for maintaining links to external resources, such as data bases etc. A full treatment is beyond our scope here

The NULL data type This data type contains only one value NULL It is case-insensitive This is a value which is returned when some expression has no value Example $capital = array ('France'=>'Paris', 'Ireland'=>'Dublin'); $capitalOfEngland = $capital[‘England’]; In this case, $capitalOfEngland would get the value NULL

Changing Data Type PHP will, in some circumstances, change the type of a datum –For example, it will treat a string of digits as a number if it finds in an arithmetic expression PHP also supports type casting <?php $myInteger = 12; $myFloat = 1.3; $result = $myFloat + (float) $myInteger; echo $result ?>

Automatic Variables (again) PHP’s automatic variables come from the following sources: –the Environment –query expressions in GET requests –message bodies in POST requests –cookies –the Server

CGI environment variables CGI environment variables are automatically available Example: What I know about you I know some things about you <?php echo " You are using $_SERVER[‘HTTP_USER_AGENT’] to view this page. "; echo " You used the $_SERVER[‘REQUEST_METHOD’] request method. "; echo " You used this request URI: $_SERVER[‘REQUEST_URI’]. "; echo " You accessed this host URI: $_SERVER[‘HTTP_HOST’]. "; echo " You used this protocol: $_SERVER[‘SERVER_PROTOCOL’]. "; ?>

Form variables (via either GET or POST) These are automatically available Example Form: Application Form <form method="POST" action="http://student.cs.ucc.ie/cs4400/jabowen/php/file9.php"> Your surname: Your address: Please send me the brochure. Example Response Generator: Thank you Thank you Thank you,. We will send our brochure to.

Control Structures – if statements if ($a > $b) echo "a is bigger than b"; if ($a > $b) {print "a is bigger than b"; $b = $a;} if ($a > $b) {print "a is bigger than b";} else {print "a is NOT bigger than b";} if ($a > $b) {print "a is bigger than b";} elseif ($a == $b) {print "a is equal to b";} else {print "a is smaller than b“;}

Example usage Example Your browser Your Browser <?php if( strstr($HTTP_USER_AGENT,"MSIE") ) { echo "You are using Internet Explorer"; } ?> to view this page. strstr is a boolean function which checks if its 2 nd argument is a substring of its 1 st

CS 3314 got here on 10 nov 2005

Control constructs -- while These are just like their counterparts in C $i = 1; while ( $i <= 10 ) { echo $i++; } $i = 0; do { print $i;} while ($i>0);

Control constructs -- for These are just like their counterparts in C for ($i = 1; $i <= 10; $i++) { print $i;}

Control constructs -- foreach These are similar their counterparts in Perl foreach(array_expression as $value) statement foreach(array_expression as $key => $value) statement

Jumping in and out of PHP mode We can can jump in and out of PHP mode even in the middle of a PHP block: <?php if(strstr($HTTP_USER_AGENT,"MSIE")) { ?> You are using Internet Explorer <?php } else { ?> You are not using Internet Explorer <?php } ?> Instead of using an echo statement to print something, we jumped out of PHP mode. Note that the logical flow of the PHP remains intact –Only one of the HTML blocks will be sent to the user.

A FORM and its handler in one file Application Handler <?php if (!$surname) { ?> <form method="POST" action="http://student.cs.ucc.ie/cs4400/jabowen/php/file012.php"> Your surname: Your address: Please send me the brochure. <?php } else { echo " Thank you, $surname. "; echo " We will write to you at $address. ";} ?>

cs 3314 got here on 13 nov 2005

One request for this resource: no Query or Message Body interzone.ucc.ie> telnet student.cs.ucc.ie 80 Trying 143.239.211.125... Connected to student.cs.ucc.ie. Escape character is '^]'. GET http://student.cs.ucc.ie/cs4400/jabowen/php/file012.php HTTP/1.1 Host: student.cs.ucc.ie

Response to request with no query or message body HTTP/1.1 200 OK Date: Fri, 08 Feb 2002 11:21:40 GMT Server: Apache/1.3.20 (Unix) PHP/4.0.6 X-Powered-By: PHP/4.0.6 Transfer-Encoding: chunked Content-Type: text/html 160 Application Handler <form method="POST" action="http://student.cs.ucc.ie/cs4400/jabowen/php/file012.php"> Your surname: Your address: Please send me the brochure. 0 Connection closed by foreign host. interzone.ucc.ie>

Another request – containing a query interzone.ucc.ie> telnet student.cs.ucc.ie 80 Trying 143.239.211.125... Connected to student.cs.ucc.ie. Escape character is '^]'. GET http://student.cs.ucc.ie/cs4400/jabowen/php/file012.php?surname=doyle HTTP/1.1 Host: student.cs.ucc.ie

Response to request containing a query HTTP/1.1 200 OK Date: Fri, 08 Feb 2002 11:31:01 GMT Server: Apache/1.3.20 (Unix) PHP/4.0.6 X-Powered-By: PHP/4.0.6 Transfer-Encoding: chunked Content-Type: text/html8 Application Handler Thank you, doyle. We will write to you at. 0 Connection closed by foreign host. interzone.ucc.ie>

Finding out about your PHP environment One of the many pre-defined PHP functions is phpinfo() Your PHP Environment In what follows, notice that mySQL support is enabled

A mysql database mysql> mysql> use cs4400db mysql> select * from student; +------------+------+------------+ | name | sex | birth | +------------+------+------------+ | john brown | m | 1980-01-05 | | bill brown | m | 1980-11-23 | +------------+------+------------+ mysql>

A PHP program which displays this database The Student Database The Student Database <?php $db = mysql_connect("localhost", "root", “myRealPassword"); mysql_select_db("cs4400db",$db); $result = mysql_query("SELECT * FROM student",$db); ?> Name Sex Position <?php while ($myrow = mysql_fetch_row($result)) { printf(" %s %s %s \n", $myrow[0], $myrow[1], $myrow[2]); } ?>

File upload form Upload a File Upload a File File to Upload: "Upload File“

File upload script <?php if ( $file1_name != "“ ) { copy("$file1", "/full/path/to/your/target/directory/$file1_name") or die("Could not copy the file! Are directory permissions correct?"); } else { die(“You did not specify an input file"); } ?> File Received File Received The following file has been received:, containing bytes and of MIME type.

Normally, when a browser sends HTML form data in the message body of a POST request, the value in the CONTENT-TYPE header is: application/x-www-form-urlencoded The new attribute, enctype, in the FORM tag tells the browser that it should send the following value in the CONTENT-TYPE header: multipart/form-data

Controlling Headers/Status lines with PHP

Sending Headers in PHP You have seen that, if you use the CGI protocol, you can have complete control over the status line and headers that are sent in a HTTP response – to do so, you must use nph files PHP does not seem to provide the same level of control –For example, it seems to prevent one sending status lines involving status codes that you have invented yourself – even though HTTP allows this Nevertheless, PHP does enable you to have some control over status lines and response headers

Sending Headers in PHP (contd.) PHP provides a built-in function, header(), which can be used to set HTTP header lines in a response message –The function name is mis-leading – it can also, within limits, be used to control the HTTP status line Format: header ( some-string [, some-boolean]); Example calls: header('WWW-Authenticate: Negotiate'); header('WWW-Authenticate: NTLM‘,false); By default, a second header of the same type will replace an earlier one of the same type –If false is sent as the optional boolean parameter, the header will not replace an earlier one of the same type

Sending Headers in PHP (contd.) PHP treats two type of call to header() in a special way If you use header() to send a Location: header, PHP will auatomatgically change the code in the status line of the response to be 302 (REDIRECT) The second special case is any header that starts with the string, "HTTP/" (case is not significant) – this will be used, within the limits of predefined standard values, to control the status line –header("HTTP/1.0 404 Not Found");

User-authentication in PHP The header() function can be used to send headers requiring authentication –This will cause a browser to pop up a username/password/realm dialog window and –When the values have been provided, send a new request back to the same page containing the appropriate information This time, some special PHP variables will be set: $PHP_AUTH_USER, $PHP_AUTH_PW and $PHP_AUTH_TYPE

User-authentication in PHP (contd.) The code below captures the user’s name and password An improved version would check this against the contents of some file <?php if (!isset( $PHP_AUTH_USER )) {header("HTTP/1.0 401 Unauthorized"); header("WWW-Authenticate: Basic realm=\“Bank Accounts\""); echo “You must identify yourself.";} else { echo " Hello $PHP_AUTH_USER. "; echo " Your password is $PHP_AUTH_PW "; } ?>

User-authentication in PHP (contd.) The PHP_AUTH variables will not be set if external authentication is enabled for that particular page. –This is to prevent a script which reveals the password for a page that was protected through a traditional external mechanism, such as the.htpasswd mechanism In this case, the $REMOTE_USER variable can be used to identify the externally-authenticated user.

Handling Cookies in PHP PHP provides a function called setcookie() which can be used to send cookies to a browser –Since cookies are sent in HTTP headers, this function must be called before any ordinary content (such as HTML) is sent Cookies sent from a broswer to a client will be converted into automatically created variables – just like those that are created to present data which come in GET and POST requests

Image Handling As well as generating dynamic HTML, PHP can generate and manipulate images <?php header("Content-type: image/png"); $string=implode($argv," "); $im = imageCreateFromPng("images/button1.png"); $orange = ImageColorAllocate($im, 220, 210, 60); $px = (imagesx($im)-7.5*strlen($string))/2; imageString($im,3,$px,9,$string,$orange); imagePng($im); imageDestroy($im); ?>

Server-side Programming in PHP. History of PHP PHP originally stood for “Personal Home Page” It started out, in 1994, as a simple preprocessor of HTML.

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Server-side Programming in PHP. History of PHP PHP originally stood for “Personal Home Page” It started out, in 1994, as a simple preprocessor of HTML.

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Presentation on theme: "Server-side Programming in PHP. History of PHP PHP originally stood for “Personal Home Page” It started out, in 1994, as a simple preprocessor of HTML."— Presentation transcript:

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