• Get together in a team of 2-3 people and decide on a PHP project that will require registration, logins, checkouts, and maintenance of data by the project.

• (Preview) For Monday, October 7, create a form for registering on a Web site and save usernames and passwords of anyone who registers. Don't let anyone use the same username twice! Construct a Web interface that lets a site administrator view the usernames and passwords.

Reading: Chapter 1, PHP Crash Course

PHP and HTML code can be interleaved (or not). The following two code segments do exactly the same thing:

 
Your name is:  
<?php  
$name = $_POST['name'];  
echo $name;  
?>   

and

  
<?php   
$name = $_POST['name'];  
echo "Your name is: ".$name;  
?>   

See string1.html/string1.php and string2.html/string2.php

Strings can be strung together with the "." operator (see above).

Strings can be delimited by either single or double quotes. If a variable appears inside a string delimited by double quotes, it is evaluated. See string3.html/string3.php and string4.html/string4.php

The following PHP code is the same as above:

<?php  
$name = $_POST['name'];  
echo "Your name is: $name";  
?>  

But this is not:

<?php  
$name = $_POST['name'];  
echo 'Your name is: $name';  
?>

• Variable names start with a $
• Except for variables defined inside functions, variable scope is global
• User inputs appear in arrays whose names are:
  $_POST: for method="post"
  $_GET: for method="get"
  $_REQUEST: includes variables from both methods
• The type of a variable is determined by its value and usage.
• A variable may contain the name of a variable.

• You can break out of a control structure with the "exit" statement.

• if statements are C- or Java-style
• except that there's an elseif:

if ($roomtype == "elite") {  
     $totalcost = ELITEPRICE*$seats; }  
elseif ($roomtype == "regular") {  
     $totalcost = REGULARPRICE*$seats; }  
elseif ($roomtype == "budget") {  
     $totalcost = BUDGETPRICE*$seats; }  
else { echo "Invalid room type"; exit; }    

For use of the above, see main1.php

• "while" and "do...while" loops are C- or Java-style.
• for loops are C- or Java-style.
• There is a "foreach" loop! (See Chapter 3)

echo '<p>$_POST is: </p>';
foreach($_POST as $entry) {
   echo "<p>$entry</p>";
}

Write html and php to duplicate the following.

Here is a Web page containing a form:

Here is the result of clicking the submit button:

Reading: Chapter 2, Storing and Retrieving Data

Reference: http://www.dartmouth.edu/~rc/help/faq/permissions.html

• Three types of file users: user (u), group (g), and other (o).
• Each type can have read permission (r), write permission (w), execute permission (x), or any combination.
• Listing files in long format (ls -l) tells you what permissions users have for the files.

1. The first field, positions 2-10, summarize the security status.
   1. The first three are user, next three are group, last three are other.
   2. They appear in order r, w, x. If a permission is not granted, the letter is -.
2. The second field names the user that owns the file (usually, the account that created it).
3. The third field names the group of the owner.

Example:

-rw-r--r--  1 nancyg  staff    286 Sep 25 13:37 README.md
-rw-r--r--@ 1 nancyg  staff  55973 Sep 24 15:52 Sept25Image1.jpg
-rw-r--r--@ 1 nancyg  staff  51725 Sep 24 16:33 Sept25Image2.jpg
-rw-r--r--@ 1 nancyg  staff  61732 Sep 24 16:56 Sept25Image3.jpg
-rw-r--r--@ 1 nancyg  staff  60748 Sep 24 19:25 Sept25Image4.jpg
-rw-r--r--  1 nancyg  staff    174 Sep 28 14:43 loop1.html
-rw-r--r--  1 nancyg  staff    258 Sep 28 14:45 loop1.php

• "chmod" lets you change file permissions. Examples

1. chmod o+x thisfile: let other execute the file.
2. chmod g+w thatfile: let any group member write the file.
3. chmod u+rwx publicfile: let the user (owner) read, write, and execute the file.
4. chmod a+r worldreadable: let anyone read the file (i.e., make it world-readable).

Function: resource fopen( string $filename, string $mode)
Reference: http://www.php.net/manual/en/function.fopen.php

• $filename

• Recommend putting it outside the Web document tree
• $_SERVER['$DOCUMENT_ROOT'] is the document root; to put it outside, you can create a directory in $_SERVER['$DOCUMENT_ROOT']/.. (the parent of document root).

* $mode

• r: read starting from beginning of file
• w, a, or x: write (over-write), append (to end), and write (quit if file already exists)
• b or t: binary (default) or text

* Returns a _resource_ . We put this in a variable to reference later; we won't manipulate it.

A problem opening a file most likely means permissions are wrong.

Functions:

• string fgets ( resource $handle [, int $length ] )
  Reads a line, returns it in a string, from the file whose "fopen" returned $handle. (It stops at $length characters if the second argument is present.)
  Reference: http://www.php.net/manual/en/function.fgets.php.
  Other commands:

1. [fgetss](http://www.php.net/manual/en/function.fgetss.php): reads a line into a string, strips tags.
2. [fgetcsv](http://www.php.net/manual/en/function.fgetcsv.php): reads a line into an array, from a csv-formatted file.
3. [fread](http://www.php.net/manual/en/function.fread.php): reads the entire file into a string, given a handle (file pointer).
4. [file_get_contents](http://www.php.net/manual/en/function.file-get-contents.php): opens and reads the entire file (given the filename) into a string.
5. [readfile](http://www.php.net/manual/en/function.readfile.php): opens and reads the file (given the filename), echoes it to standard out, and closes it. Example: testread1.php
6. [fpassthru](http://www.php.net/manual/en/function.fpassthru.php): reads and outputs the file, given a handle (file pointer). Example: testread2.php
7. [file](http://www.php.net/manual/en/function.file.php): opens and reads the file into an array (one line per array entry). Example: testread3.php
8. [fgetc](http://www.php.net/manual/en/function.fgetc.php): reads the file one character at a time.

When reading a line or character at a time, you need to know when to stop:
Function: bool feof ( resource $handle )
Returns true if you have reached the end of file.

Functions:

• int fwrite ( resource $handle , string $string [, int $length ] )
  Writes the string to the file designated by $handle, up to $length bytes.
  Reference: http://www.php.net/manual/en/function.fwrite.php.
  Other commands:

1. [file_put_contents](http://www.php.net/manual/en/function.file_put_contents.php): puts the entire contents of a string in a file, given the filename.

Function: bool fclose ( resource $handle )
Closes the designated file.
Reference: http://www.php.net/manual/en/function.fclose.php

Write php programs similar to testread1.php, testread2.php, and testread3.php to demonstrate the differences between fgets, fgetss, and fgetcsv.

• An array is a data structure with multiple entries.
• An array can have one, two, or more dimensions.
• Array entries can be accessed by position (or positions, if multi-dimensional). Indexing is zero-based: $myarray[0] is the first element of the array.
• Regular (as opposed to ragged) multi-dimensional arrays are indexed as usual: $myarray[$i][$j]...
• You can use an array entry such as $myarray[$i] anyplace you can use a variable.
• Using loops to access an array:

for ($i=0; $i<10, $i++) {
    echo $myarray[$i];
}

• Associative addressing (like a dictionary in Python). Entries can be identified by keys rather than numeric indexes.
• Array initialization

1. Numeric indexes: $myarray = array('a', 'b', 'c');
2. Associative: $myarray = array('a'=>0, 'b'=>0, 'c'=>0);
3. Range operator: $myarray = range(1,10); Also:
   • range (10, 100, 2);
   • range ('a', 'z');
   • range ('a', 'z', 3);

* Using loops

• [foreach](http://www.php.net/manual/en/control-structures.foreach.php)

      foreach ($myarray as $key=>$value) {
          echo $key."=>".$value."<br />";
      }
  

  See testarray1.php.
• [each](http://www.php.net/manual/en/function.each.php)

      $myarray = range('a', 'z');
      while (list($key, $value) = each($myarray)) {
          echo $key." => ".$value."<br />";
      }
  

  See testarray2.php and testarray3.php.

* Types can be mixed in arrays. See testarrayshape1.php. * [Array operators](http://php.net/manual/en/language.operators.array.php)

• + (union): combine two arrays, to include all entries from both arrays. If a key of the right-hand array matches a key of the left-hand array, include only the entry from the left-hand array. See testarray4.php and testarray5.php.
• == (equals): true if the arrays have the same key/value pairs. See testarray6.php.

1. Write a loop that reads through a file whose handle is $fp, one line at a time, and outputs "Contains a special character" if the line contains a special character and prints "Does not contain a special character" if it does not. Each line of the file should produce a line on the output html page.

2. What mode do you use with fopen to:
   a. Open a file for adding more information to it (without erasing any)?
   b. Open a file for writing over the information in it?
   c. Open a file for reading?
   d. Operate on a file in a binary-safe manner?

3. What does binary-safe mean when you are reading and writing files?

4. What read and write operations do you use to read or write one line of a file at a time? How do you create a new line in a file using php?

5. Write php code to initialize an array with entries:

Key	Value
alpha	10
beta	1
gamma	100

and then loop through the table, outputting one line containing each key and value pair.

6. Given an array $array1 with the above value and a second array $array2 with the following value:

Key	Value
alpha	5
delta	7
beta	9

What does the statement

$array3 = $array1+$array2; 

do?

7. Here's the code we did in class to read & print a file:

<?php

if (!$fp=@fopen("data", "r"))
{
	print("Try again later");
	exit;
}

while (!feof($fp)) {
	if (!$string=@fgets($fp))
	{
		print("Read error");
		exit;
	}
	list($user,$password) = explode(" ", $string);
	print ($user." ".$password."
");
}
fclose($fp);
?>