PHP - Echo

02:21 
<?php
$myiString = "Hi!";
echo $myiString;
echo "<h5>I love  PHP!</h5>";
?>
 

Display:

Hi!
I love  PHP!
 A simple form example
 
 
1 <html>
 2 <head>
 3  <title>Building a Form</title>
 4 </head>
 5 <body>
 6  <form action="<?php echo($_SERVER['PHP_SELF']); ?>"
 7        method="get">
 8   <label>
 9         Search: <input type="text" name="search" />
 10    </label>
 11      <input type="submit" value="Go!" />
 12  </form>
 13 </body>
 14 </html>
 
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PHP Configuration Directives

02:09
Although the focus of this book is application security, there are a few configuration directives with which any security-conscious developer should be familiar. The configuration of PHP can affect the behavior of the code you write as well as the techniques that you employ, and your responsibilities might extend slightly beyond the application on occasion.

The configuration of PHP is primarily dictated by a file called php.ini. This file contains many configuration directives, and each of these affects a very specific aspect of PHP. If this file is absent, or if a particular configuration directive is absent from the file, a default value is used.
If you do not know the location of your php.ini file, you can use phpinfo( ) to determine where PHP expects to find it:
 
<?php

    phpinfo();

    ?>
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PHP Sessions

02:05
The session_start( ) function is used to create a new session. A session is unique to the interaction between a browser and a web database application. If you use your browser to access several sites at once, you'll have several unrelated sessions. Similarly, if several users access your application each has their own session. However, if you access an application using two browsers (or two browser windows) at the same time, in most cases the browsers will share the same session; this can lead to unpredictable behavior—that's the reason why many web sites warn against it.

The first time a user requests a script that calls session_start( ), PHP generates a new session ID and creates an empty file to store session variables. PHP also sends a cookie back to the browser that contains the session ID. However, because the cookie is sent as part of the HTTP headers in the response to the browser, you need to call session_start( ) before any other output is generated

The session identifier generated by PHP is a random string of 32 hexadecimal digits, such as fcc17f071bca9bf7f85ca281094390b4. When a new session is started, PHP creates a session file, using the session identifier, prefixed with sess_, for the filename. For example, the filename associated with our example session ID on a Unix system is /tmp/sess_fcc17f071bca9bf7f85ca281094390b4.

Using Session Variables

The session_start( ) function is also used to find an existing session. If a call is made to session_start( ), and a session has previously been started, PHP attempts to find the session file and initialize the session variables. PHP does this automatically by looking for the session cookie in the browser request whenever you call session_start( ). You don't need to do anything different when starting a new session or restoring an existing one. Even if the identified session file can't be found, session_start( ) simply creates a new session file.


A simple PHP script that uses a session
<?php

  require_once "HTML/Template/ITX.php";



  // This call either creates a new session or finds an existing one.

  session_start( );



  // Check if the value for "count" exists in the session store

  // If not, set a value for "count" and "start"

  if (!isset($_SESSION["count"]))

  {

    $_SESSION["count"] = 0;

    $_SESSION["start"] = time( );

  }



  // Increment the count

  $_SESSION["count"]++;



  $template = new HTML_Template_ITX("./templates");

  $template->loadTemplatefile("example.10-2.tpl", true, true);



  $template->setVariable("SESSION", session_id( ));

  $template->setVariable("COUNT", $_SESSION["count"]);

  $template->setVariable("START", $_SESSION["start"]);

  $duration = time( ) - $_SESSION["start"];

  $template->setVariable("DURATION", $duration);



  $template->parseCurrentBlock( );



  $template->show( );

?>


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Length of a String

02:02
The length property of a string is determined with the strlen( ) function, which returns the number of eight-bit characters in the subject string:
integer strlen(string subject)
We used strlen( ) earlier in the chapter to compare string lengths. Consider another simple example that prints the length of a 16-character string:
print strlen("This is a String");  // prints 16
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Creating Arrays

02:01
PHP provides the array( ) language construct that creates arrays. The following examples show how arrays of integers and strings can be constructed and assigned to variables for later use:
$numbers = array(5, 4, 3, 2, 1);

$words = array("Web", "Database", "Applications");



// Print the third element from the array of integers: 3

print $numbers[2];



// Print the first element from the array of strings: "Web"

print $words[0];

By creating arrays this way, PHP assigns integer keys, or indexes to each element. By default, the index for the first element in an array is 0—this may seem odd but think of the index as an offset from the starting position in an array. The values contained in an array can be retrieved and modified using the bracket [ ] syntax. You can also create an array by assigning elements to a new, unset variable. The following code fragment illustrates the bracket syntax with an array of strings:
$newArray[0] = "Potatoes";

$newArray[1] = "Carrots";

$newArray[2] = "Spinach";



// Replace the third element

$newArray[2] = "Tomatoes";

In this example, PHP automatically treats $newArray as an array without a call to array( ).
An empty array can be created by assigning to a variable the return value of array( ). Values can then be added using the bracket syntax. PHP automatically assigns the next numeric index as the key (the largest integer key value plus one) when a key isn't supplied. The result of the following fragment is an array containing three items.
$shopping = array( );



$shopping[] = "Milk";

$shopping[] = "Coffee";

$shopping[] = "Sugar";

It's also easy to print individual element values themselves:
print $shopping[0];   // prints "Milk"

print $shopping[1];   // prints "Coffee"

print $shopping[2];   // prints "Sugar"
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PHP Zip File Functions

03:10

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PHP MySQL Functions

02:56

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PHP Date / Time Functions

02:49

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PHP HTTP Functions

23:40

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PHP Array Functions

23:14
  • array_change_key_case — Changes all keys in an array
  • array_chunk — Split an array into chunks
  • array_combine — Creates an array by using one array for keys and another for its values
  • array_count_values — Counts all the values of an array
  • array_diff_assoc — Computes the difference of arrays with additional index check
  • array_diff_key — Computes the difference of arrays using keys for comparison
  • array_diff_uassoc — Computes the difference of arrays with additional index check which is performed by a user supplied callback function
  • array_diff_ukey — Computes the difference of arrays using a callback function on the keys for comparison
  • array_diff — Computes the difference of arrays
  • array_fill_keys — Fill an array with values, specifying keys
  • array_fill — Fill an array with values
  • array_filter — Filters elements of an array using a callback function
  • array_flip — Exchanges all keys with their associated values in an array
  • array_intersect_assoc — Computes the intersection of arrays with additional index check
  • array_intersect_key — Computes the intersection of arrays using keys for comparison
  • array_intersect_uassoc — Computes the intersection of arrays with additional index check, compares indexes by a callback function
  • array_intersect_ukey — Computes the intersection of arrays using a callback function on the keys for comparison
  • 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 or a subset of the keys of an array
  • array_map — Applies the callback to the elements of the given arrays
  • array_merge_recursive — Merge two or more arrays recursively
  • array_merge — Merge one or more arrays
  • 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_product — Calculate the product of values in an 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_reduce — Iteratively reduce the array to a single value using a callback function
  • array_replace_recursive — Replaces elements from passed arrays into the first array recursively
  • array_replace — Replaces elements from passed arrays into the first array
  • array_reverse — Return an array with elements in reverse order
  • array_search — Searches the array for a given value and returns the corresponding key if successful
  • 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_udiff_assoc — Computes the difference of arrays with additional index check, compares data by a callback function
  • array_udiff_uassoc — Computes the difference of arrays with additional index check, compares data and indexes by a callback function
  • array_udiff — Computes the difference of arrays by using a callback function for data comparison
  • array_uintersect_assoc — Computes the intersection of arrays with additional index check, compares data by a callback function
  • array_uintersect_uassoc — Computes the intersection of arrays with additional index check, compares data and indexes by a callback functions
  • array_uintersect — Computes the intersection of arrays, compares data by a callback function
  • array_unique — Removes duplicate values from an array
  • array_unshift — Prepend one or more elements to the beginning of an array
  • array_values — Return all the values of an array
  • array_walk_recursive — Apply a user function recursively to every member of an array
  • array_walk — Apply a user function to every member of an array
  • array — Create 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 all elements in an array, or something in an object
  • 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 — Checks if a value exists in an array
  • key — Fetch a key from an 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
  • natcasesort — Sort an array using a case insensitive "natural order" algorithm
  • natsort — Sort an array using a "natural order" algorithm
  • next — Advance the internal array pointer of an array
  • pos — Alias of current
  • 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 — Alias of count
  • 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

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