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Server-side Programming in PHP
| Date post: | 21-Dec-2015 |
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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 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
<html>
<head>
<title>PHP Test</title>
</head>
<body>
<?php echo “<p>Hello World</p>"; ?>
</body>
</html>
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
<?php … ?>
• The text inside the tag is PHP code
<?php echo “<p>Hello World</p>"; ?>
• 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
<p>Hello World</p>
Suppose we request this fileinterzone.ucc.ie> telnet student.cs.ucc.ie 80
Trying 143.239.211.125...
Connected to student.cs.ucc.ie.
Escape character is '^]'.
GET /cs4400/jabowen/php/file1.php HTTP/1.1
Host: student.cs.ucc.ie
Here is the response
HTTP/1.1 200 OKDate: Wed, 06 Feb 2002 12:34:15 GMTServer: Apache/1.3.20 (Unix) PHP/4.0.6X-Powered-By: PHP/4.0.6Transfer-Encoding: chunkedContent-Type: text/html
58 <html><head><title>PHP test</title></head><body><p>Hello world!</p></body></html>
0
Connection closed by foreign host.
interzone.ucc.ie>
• cs 3314 got here on 27 oct 2005
Note following in response:
• Chunked transfer-encoding is used– because the httpd demon does not know,
before executing the PHP content, how long the message body will be
• PHP code has been replaced, in the message body, by its output
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<?php … ?>
• 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:
<? … ?><% … %><script language=“php”> … </script>
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<html>
<head>
<title>Greetings</title>
</head>
<body>
<h1>Greetings</h1>
<p>
<?php $person = "Tom";
$Person = "Dick";
echo "Hello $person and $Person";
?>
</p>
</body>
</html>
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
<html><head><title>Your browser</title></head><body><h1>Your Browser</h1><p>You are using <?php echo $HTTP_USER_AGENT; ?>to view this page.</p></body></html>
A warning about pre-defined variables
• The way in which PHP supports pre-defined variables has changed recently.
• This will be discussed in a future lecture
Data Types in PHP
• PHP supports eight primitive data types• There are four scalar types
– boolean– integer– floating-point number– string
• There are two structured types– array– object
• There are two special data types– resource– NULL
• The programmer does not specify the type of a variable– a variable’s type is determined from the context of its usage
Booleans
• The boolean data type admits two values– true (case-insensitive)– false (case-insensitive)
• Example usage$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
• cs 3314 got here on 3 nov 2005
Single-quoted Strings
• In single-quoted strings, single-quotes and backslashes must be escaped with a preceding backslash
• Example usageecho '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 2nd 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 arraysarray( )
• 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 specificationarray( [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<html>
<head><title>Array Demo</title></head>
<body>
<h1>Array Demo</h1>
<p>
<?php
$capital = array ('France'=>'Paris','Ireland'=>'Dublin');
echo 'The capital of Ireland is ';
echo $capital['Ireland'];
?>
</p>
</body>
</html>
Array Example 2<html>
<head><title>Array Demo</title></head>
<body>
<h1>Array Demo</h1>
<p>
<?php
$capital = array ('France'=>'Paris', ‘Ireland'=>'Dublin');
echo "The various capitals are\n<ul>";
foreach ($capital as $city) { echo "<li>$city</li>"; };
echo "</ul>"
?>
</p>
</body>
</html>
Array Example 3<html>
<head><title>Array Demo</title></head>
<body>
<h1>Array Demo</h1>
<p>
<?php
$capital = array ('France'=>'Paris', 'Ireland'=>'Dublin');
echo "The various capitals are\n<ul>";
foreach ($capital as $country => $city)
{ echo "<li>The capital of $country is $city</li>"; };
echo "</ul>"
?>
</p>
</body>
</html>
Array Example 4<html>
<head>
<title>Details about Fred</title>
</head>
<body>
<h1>Details about Fred</h1>
<?php
$ages = array ("Fred" => 2, "Tom"=> 45);
$parents = array ("Fred" => array("father" => "Tom", "mother"=>"Mary"));
print "<p> Fred's age is ";
print $ages["Fred"];
print ".</p>";
print "<p>His father is ";
print $parents["Fred"]["father"];
print ".</p>";
?>
</body>
</html>
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
Cs 3314 got here on 7/11/2005
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:
<html>
<head>
<title>What I know about you</title>
</head>
<body>
<h1>I know some things about you</h1>
<?php
echo "<p>You are using $HTTP_USER_AGENT to view this page.</p>";
echo "<p>You used the $REQUEST_METHOD request method.</p>";
echo "<p>You used this request URI: $REQUEST_URI.</p>";
echo "<p>You accessed this host URI: $HTTP_HOST.</p>";
echo "<p>You used this protocol: $SERVER_PROTOCOL.</p>";
?>
</body>
</html>
Form variables (via either GET or POST)• These are automatically available• Example Form:
<html><head><title>Application Form</title></head><body><form method="POST" action="http://student.cs.ucc.ie/cs4400/jabowen/php/file9.php"><p>Your surname: <input type="text" name="surname“></p><p>Your address: <input type="text" name="address“></p><button type="submit">Please send me the brochure.</button></form></body></html>
• Example Response Generator:<html><head><title>Thank you</title></head><body><h1>Thank you</h1><p>Thank you,<?php echo $surname ?>.We will send our brochure to <?php echo $address ?>.</p></body></html>
Control Structures – if statements• if ($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 == $b)
{print "a is equal to b";}
else {print "a is smaller than b“;}
Example usage• Example
<html><head><title>Your browser</title></head><body><h1>Your Browser</h1><p> <?php if( strstr($HTTP_USER_AGENT,"MSIE") ) { echo "You are using Internet Explorer"; }?>to view this page.</p></body></html>
• strstr is a boolean function which checks if its 2nd argument is a substring of its 1st
• 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"))
{ ?> <p>You are using Internet Explorer</p> <?php }
else { ?> <p>You are not using Internet Explorer</p> <?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<html><head><title>Application Handler</title></head><body><?phpif (!$surname) { ?> <form method="POST"
action="http://student.cs.ucc.ie/cs4400/jabowen/php/file012.php"><p>Your surname: <input type="text" name="surname"></p><p>Your address: <input type="text" name="address"></p><button type="submit">Please send me the brochure.</button></form>
<?php } else { echo "<p>Thank you, $surname.</p>"; echo "<p> We will write to you at $address.</p>";} ?></body></html>
• 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 bodyHTTP/1.1 200 OKDate: Fri, 08 Feb 2002 11:21:40 GMTServer: Apache/1.3.20 (Unix) PHP/4.0.6X-Powered-By: PHP/4.0.6Transfer-Encoding: chunkedContent-Type: text/html
160<html><head><title>Application Handler</title></head><body><form method="POST" action="http://student.cs.ucc.ie/cs4400/jabowen/php/file012.php"><p>Your surname: <input type="text" name="surname"></p><p>Your address: <input type="text" name="address"></p><button type="submit">Please send me the brochure.</button></form></body></html>
0Connection 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/html
88
<html>
<head><title>Application Handler</title></head>
<body>
<p>Thank you, doyle.</p><p> We will write to you at .</p></body>
</html>
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()
<html> <body> <h1>Your PHP Environment</h1><?php phpinfo(); ?> </body> </html> • In what follows, notice that mySQL
support is enabled
A mysql databasemysql>
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<html>
<head><title>The Student Database</title></head>
<body>
<h1>The Student Database</h1>
<?php
$db = mysql_connect("localhost", "root", “myRealPassword");
mysql_select_db("cs4400db",$db);
$result = mysql_query("SELECT * FROM student",$db); ?>
<table rules=all>
<thead><tr><th>Name</th><th>Sex</th><th>Position</th></tr></thead>
<tbody>
<?php
while ($myrow = mysql_fetch_row($result))
{ printf("<tr><td>%s</td><td>%s</td><td>%s</td></tr>\n",
$myrow[0], $myrow[1], $myrow[2]); } ?>
</tbody>
</table>
</body>
</html>
• cs 3314 got here on 17 nov 2005
Cs3314 GOT TO HERE ON 9/12/2004
File upload form<html><head><title>Upload a File</title></head><body><h1>Upload a File</h1>
<form enctype="multipart/form-data" method="post" action="uploadFile.php">
<p>File to Upload:<input type="file" name=“file1" size="30"></p>
<p><button type="submit“> "Upload File“</button></p>
</form></body></html>
• cs 3314 got here on 21 nov 2005
File upload script<?phpif ( $file1_name != "“ ) { copy("$file1", "/full/path/to/your/target/directory/$file1_name") or die("Could not copy the file! Are directory permissions correct?"); } else { die(“You did not specify an input file"); } ?><html><head><title>File Received</title><body>
<h1>File Received</h1>
<p>The following file has been received: <?php echo “$file1_name"; ?>, containing <?php echo “$file1_size"; ?> bytes and of MIME type <?php echo “$file1_type"; ?>.</p>
</body></html>
• 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");
• CS 607 got here on 27 Feb 2003
• Igat wanpela meri em i slip finis long displa de
• Introduced php handling of multiple selections in forms
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 "<p>Hello $PHP_AUTH_USER.</p>";
echo "<p>Your password is $PHP_AUTH_PW </p>"; }
?>
• CS 607 got here on 4 March 2003
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);
?>
