1. 12 – PHP Contd. Informatics Department Parahyangan Catholic University

2.  Super globals were introduced in PHP 4.1.0, and are built- in variables that are always available in all scopes  Several predefined variables in PHP are superglobals  The PHP super global variables are:  $GLOBALS  $_SERVER  $_REQUEST  $_POST  $_GET  $_FILES  $_ENV  $_COOKIE  $_SESSION

3.  $GLOBALS is a PHP super global variable which is used to access global variables from anywhere in the PHP script (also from within functions or methods).  PHP stores all global variables in an array called $GLOBALS[index]. The index holds the name of the variable.

4.  Example:

5.  $_SERVER is a PHP super global variable which holds information about headers, paths, and script locations.  The entries in this array are created by the web server. There is no guarantee that every web server will provide same set of variables  Reference: http://php.net/manual/en/reserved.variables.server.php

6.  Example: <?php /*The filename of the currently executing script, relative to the document root*/ echo $_SERVER['PHP_SELF']; echo " "; /*The name of the server host*/ echo $_SERVER['SERVER_NAME']; echo " "; /*The IP address of the server*/ echo $_SERVER['SERVER_ADDR']; echo " "; /*Which request method was used to access the page, i.e. GET or POST*/ echo $_SERVER['REQUEST_METHOD']; ?>

7.  $_REQUEST is used to collect data from a submitted HTML form. <?php if (isset($_REQUEST['fname'])){ $name = $_REQUEST['fname']; echo "Hello $name !!"; } else{ ?> Name: <?php } ?>

9.  $_POST is used to collect data from a submitted HTML form with method="post".  $_POST is also widely used to pass variables.  Example: <?php if ($_SERVER['REQUEST_METHOD'] == 'POST'){ $name = $_POST['fname']; echo "Hello $name !!"; } else{ ?> <?php } ?>

10.  $_GET can be used to collect data from a submitted HTML form with method="get“  $_GET can also collect data sent in the URL

11.  Example: <?php if (isset($_GET['fname'])){ $name = $_GET['fname']; echo "Hello $name !!"; } else{ ?> Name: <?php } ?>

12.  $_REQUEST is an associative array that by default contains the contents of $_GET, $_POST and $_COOKIE  There is no guarantee that the $_REQUEST data comes from the source we wanted, thus it is more reliable to use $_POST or $_GET or $_COOKIE

13. <?php if (isset($_REQUEST['fname'])){ $name = $_REQUEST['fname']; echo "REQUEST : Hello $name !! "; $name = $_GET['fname']; echo "GET : Hello $name !! "; $name = $_POST['fname']; echo "POST : Hello $name !! "; } else{ ?> Name: <?php } ?> Sent through GET Sent through POST

14.  There is no guarantee which fname will be recorded in $_REQUEST

15.  Suppose we have form like this: Name: *required

16.  Since the validation is done by HTML (client side), it is easy to override. One can rewrite the HTML code without the required attribute.  Thus it is important to validate the form’s input at the server’s side.  Client side form validation is useful for giving the user a quick feedback whether he/she has filled the form correctly

17.  Example: <?php if ($_SERVER['REQUEST_METHOD'] == 'POST'){ if(isset($POST['fname'])){ $name = $_POST['fname']; echo "Hello $name !! "; } else{ echo "Error: no name was provided!"; } else{ ?> <?php } ?>

18.  File handling is an important part of any web application. You often need to open and process a file for different tasks.  Our discussion includes:  Reading a file’s content  Writing to a file  Uploading a file

19.  When we are manipulating files we must be very careful.  We can do a lot of damage if we do something wrong. Common errors are:  editing the wrong file  filling a hard-drive with garbage data  eleting the content of a file by accident

20.  The readfile() function reads a file and writes everything in it to the output buffer (i.e., echoes everything in it)  The readfile() function returns the number of bytes read on success

21.  Example:  myfile.txt contains: <?php readfile("myfile.txt"); ?> <?php $num = readfile("myfile.txt"); echo " $num"; ?> abcdefghijkl

22.  The file_get_contents() reads entire file into a string  Example:  More options, see: http://php.net/manual/en/function.file-get-contents.php <?php $str = file_get_contents("myfile.txt"); for($i=0; $i<strlen($str); $i++) echo $str[$i]." "; ?>

23.  The file() function reads the entire file into an array. One line per array’s element.  Example:  myfile.txt contains: abcdefghijkl hello world! 12345 <?php $lines = file("myfile.txt"); for($i=0; $i<sizeof($lines); $i+=2) echo $lines[$i]." "; ?>

24.  The fopen() function opens a file or URL for reading. It returns a file handle.  Syntax: fopen(filename, mode)

25. ModeR/W ?File doesn’t existFile already existPointer at rread onlyfailed to opensuccessfully opens itbeginning r+read & writefailed to opensuccessfully opens itbeginning wwrite onlycreates new filereplace with a new filebeginning w+read & writecreates new filereplace with a new filebeginning awrite onlycreates new fileappends to existing fileend a+read & writecreates new fileappends to existing fileend xwrite onlycreates new filefailed to replacebeginning x+read & writecreates new filefailed to replacebeginning cwrite onlycreates new fileappends to existing filebeginning c+read & writecreates new fileappends to existing filebeginning

26.  Example: <?php $handle = fopen("myfile.txt", "r"); if($handle){ echo "file successfully opened"; } else{ echo "file not found"; } ?>

27. <?php $handle = fopen("myfile2.txt", "r"); if($handle){ echo "file successfully opened"; } else{ echo "file not found"; } ?>  Example:

28.  How to remove warning messages ?  fix the error that causes it !  control which PHP errors are reported using the error_reporting() function  Example: error_reporting(E_ERROR | E_PARSE); tells PHP to only shows fatal run-time errors and parse errors. Complete reference: http://php.net/manual/en/errorfunc.constants.php

29.  The fclose() function is used to close an opened file.  It is important to close an opened file after we finish using it (reading/writing), so that other program can access it.  Example: fclose($handle);

30.  The fprintf() function writes a formatted string to a stream (i.e., opened file)  Syntax: fprintf(handle, format, [variables])  Works like printf in Java/C

31.  Example:  After running the PHP file, myfile2.txt contains: <?php $PI = 3.141592; $x = 5; $handle = fopen("myfile2.txt", "w"); fprintf($handle, "x=%d\nPI=%.3f", $x, $PI); fclose($handle); ?> x=5 PI=3.142

32.  The printf() function writes a formatted string to the output buffer (i.e., like echo)  The sprintf() returns a formatted string

33.  Example: <?php $PI = 3.141592; $x = 5; $str = ""; $str = sprintf("x=%d\nPI=%.3f", $x, $PI); printf("String str now contains: %s ", $str); ?>

34.  The fscanf() function parses input from a file according to a format  Syntax: fscanf(handle, format, [variables])  Any whitespace in the format string matches any whitespace in the input stream. This means that even a tab \t in the format string can match a single space character in the input stream.

35.  Example:  file myfile.txt contains: Monday, 26 October 2015 3.14 22/7 Alice Bob <?php $handle = fopen("myfile.txt", "r"); fscanf($handle, "%[^,], %d %s %d", $day, $date, $month, $year); printf("%s %d %s %d ", $day, $date, $month, $year); ?> %[^,] is a regular expression that means read a string which doesn’t contain a coma (,) coma and space at file input is matched to coma and space in scanf’s formatting string

36.  Each call to fscanf() reads one line from the file.  Example: <?php $handle = fopen("myfile.txt", "r"); fscanf($handle, "%[^\,], %d %s ", $day, $date, $month); fscanf($handle, "%d", $year); printf("%s %d %s %d ", $day, $date, $month, $year); ?> Monday, 26 October 2015 3.14 22/7 Alice Bob

37.  If fscanf() used with >2 arguments (that is, we specify the variables to store the parsed values), it returns the number of successfully parsed values. It returns ≤ 0 when no values parsed.  Example:  myfile.txt contains: 123 456 <?php $handle = fopen("myfile.txt", "r"); $res1 = fscanf($handle, "%d", $num1); $res2 = fscanf($handle, "%d", $num2); $res3 = fscanf($handle, "%d", $num3); printf("%d %d ", $res1, $num1); printf("%d %d ", $res2, $num2); printf("%d %d ", $res3, $num3); fclose($handle); ?>

38.  The sscanf() function works similarly to fscanf(), except that it parses input from a string  Example: <?php $handle = fopen("myfile.txt", "r"); fscanf($handle, "%[^\n\r]",$str); printf("Variable str contains: %s ", $str); sscanf($str, "%[^\,], %d %s %d", $day, $date, $month, $year); printf("%s %d %s %d ", $day, $date, $month, $year); fclose($handle); ?> Monday, 26 October 2015 3.14 22/7 Alice Bob

39.  The feof() function checks if the "end-of-file" (EOF) has been reached. It is useful for looping through data of unknown length.  Example: <?php $handle = fopen("myfile.txt", "r"); $i = 1; while(!feof($handle)){ fscanf($handle, "%[^\n\r]", $str); printf("Line %d: %s ", $i++, $str); } fclose($handle); ?> Monday, 26 October 2015 3.14 22/7 Alice Bob

40.  Example: <?php $handle = fopen("myfile.txt", "r"); $i = 1; while(!feof($handle)){ $res = fscanf($handle, "%[^\n\r]", $str); printf("Line %d: %d [%s] ", $i++, $res, $str); } fclose($handle); ?> Monday, 26 October 2015 3.14 22/7 Alice Bob Charlie

41.  The fgets() function reads one line from a file, including the new line character (\n\r). It can reads an empty line.  Example: <?php $handle = fopen("myfile.txt", "r"); $i = 1; while(!feof($handle)){ $str = fgets($handle); printf("Line %d: [%s] ", $i++, $str); } fclose($handle); ?>

42. Monday, 26 October 2015 3.14 22/7 Alice Bob Charlie why there is a space on line 4 ? fgets reads a line, including the \n\r character. New line on HTML code means a space in the web page fgets reads a line, including the \n\r character. New line on HTML code means a space in the web page