• Overview:
  • Most HTTP servers can be configured to execute PHP programs
  • Most HTTP servers look for PHP code in files with a .php extension
• The Process on the Server:
  • Some parts of the .php file (i.e., most HTML elements, CSS) are just inserted into the HTTP response
  • Some parts of the .php file (see below) are executed and the output is inserted into the HTTP response
• Different Ways to Identify PHP Code:
  • Put it between a <?php and ?> (XML/XHTML style)
  • Put it in the body of a script element (HTML style)
  • Put it between a <? and ?>
  • Put it between a <% and %> (ASP style)

• Examples of the echo Statement:
  • echo "<p>Hello world!</p>"; echo "<p>Hello $name.</p>"; // $name is evaluated echo "<p>Hello find($name).</p>"; // find() is not evaluated but $name is evaluated echo $name; echo '<p>Hello $name.</p>'; // $name is not evaluated
• Using print:
  • Has only one string parameter
  • Can be used as a statement like echo (i.e., without parentheses)
  • Can be used as a function (i.e., with parentheses)
• Using printf():
  • printf(formatstring [,parameters]...)

Loading the PHP Classes/Functions

Insertion of the Code Fragment

• Overview of the $_SERVER Array:
  • Is an associative array that is populated with information about the request
  • Has superglobal scope
• Important Elements of the $_SERVER Array:
  • ["REQUEST_METHOD"] - either "GET" or "POST"
  • ["SERVER_PROTOCOL"]
  • ["SERVER_NAME"]
  • ["SERVER_PORT"]
  • ["PATH_INFO"] and ["PATH_TRANSLATED"]
  • ["QUERY_STRING"]
  • ["CONTENT_TYPE"]
  • ["CONTENT_LENGTH"]
  • ["REMOTE_HOST"] and ["REMOTE_ADDR"]

• The $_GET Array:
  • Is an associative array that is populated with information from the query string
  • Has superglobal scope
• The $_POST Array:
  • Is an associative array that is populated with form data from the data section (when the POST has a Content-Type of application/x-www-form-urlencoded or multipart/form-data)
  • Has superglobal scope
  • Some elements are themselves arrays (e.g., if a user checks more than one alternative in a select element or more than one checkbox)

• The $_COOKIE Array:
  • A superglobal associative array containing the HTTP cookies that have been set
• The setcookie() Function:
  • Sets a cookie to be sent
  • Must be called before any output is generated (since cookies are part of the HTTP header)
  • Syntax: setcookie(name [, value [, expiration [, path [, domain [, secure [, httponly]]]]]] )

• The header() Function:
  • Sets a header to be sent (specified as a "name: value")
  • Must be called before any output is generated (since HTTP headers are at the beginning of the response)
• A Warning:
  • Remember that some header information will be set automatically (e.g., Content-Length)

• Value Checking:
  • is_null() returns true if the parameter is NULL
  • isset() returns true if the parameter is set and not NULL
• Type Checking/Conversion/Enforcement:
  • is_array(), is_bool(), is_float(), is_int(), is_object(), and is_string()
  • boolval(), floatval(), and intval()
• Encoding Functions:
  • htmlentities()
  • urlencode()/urldecode() and rawurlencode()/rawurldecode()
• Tokenizing/Parsing:
  • parse_url()
• Validation/Sanitization:
  • filter_var()