Server-Side Scripting: Chapter 1

• Server-Side Scripting is the first chapter. Included in the chapter are:
  • Introduction to server-side scripting
  • Server-side scripting languages
  • Use Basic Syntax
  • Write Comments
  • Utilize Variables
  • Manipulate Strings
  • Manipulate Numbers
  • Work with constants

Introduction to Server-Side Scripting

• Web communication uses HTTP (Hyper Text Transfer Protocol) between a client and a server.
• Requests range from a simple get request (fetch static content) to post and delete requests (add/delete resources).
• Each request/response has a header and an optional body.
• Servers remain active, waiting for and handling client requests.

Communication Scenarios

• Communication Scenarios include communication between files and the Web Server, as well as database access.
• Static content includes files processed directly through the web server.
• Dynamic content uses web applications to access files and databases to deliver a customized output.

Server-Side vs Client-Side Scripting Languages

• Client-side scripts:
  • Executed by the client (browser).
  • They are used for the appearance/behavior of a webpage.
  • Limited access to the underlying operating system.
  • Rendering issues can occur differently depending on browser.
• Server-Side Scripting Languages:
  • Scripts are executed on the server and require a server-side scripting engine.
  • They have full access to the server's operating system.
  • Languages include PHP, Python, Ruby, C#, and JavaScript (Node.js).

Uses for Server-Side Scripting

• Dynamic webpages:
  • Authentication, authorization, and session tracking.
  • Content personalization/customization based on user behavior.
  • Template-driven page generation.
  • Handling POST form input.
  • Communication with other programs, libraries, and APIs (e.g., sending emails).

PHP

• PHP (Hypertext Protocol) is free, open-source language for web pages suitable for web development.
• It can run on various platforms and works with most servers, using ".php" file extensions.
• PHP can perform system functions, such as creating/modifying/closing files.
• PHP functions include adding/deleting/modifying elements within a database.
• It can restrict user access to specific webpages.
• It offers data encryption and runs on Windows, Linux, and macOS.
• PHP requires an Apache web server or XAMPP to run; it is interpreted on the server before browser delivery.

Apache Web Server

• A Web server accepts requests via HTTP/HTTPS.
• The Apache HTTP Server is open-source, free and cross-platform.
• It manages various files, including HTML, images, MP3s, and RSS feeds.
• It dynamically generates non-static files using server-side programs like PHP.
• It is released under Apache License 2.0.

Local Web Servers

• WAMP, MAMP, and LAMP are software packages used to setup local web servers for development.
  • WAMP (Windows, Apache, MySQL, PHP) for Windows.
  • MAMP (Mac, Apache, MySQL, PHP) for Mac.
  • LAMP (Linux, Apache, MySQL, PHP) for Linux.
• These servers are easy to set up, but not secure enough for public use (development and testing purposes only).

XAMPP

• XAMPP is a free and open-source web server solution package mainly for local web application testing.
• X = Cross-platform
• A = Apache Server
• M = MariaDB/MySQL
• P = PHP
• P = Perl

Benefits of XAMPP

• Development and website testing locally, which reduces the need for live internet connections.
• It supports backend development utilizing PHP and MySQL/MariaDB.
• It works with all operating systems including: Windows, macOS, and Linux.
• Apache, MySQL, and PHP are bundled together, simplifying manual setup and configuration.
• It allows for local website and application testing, before launch.

PHP Syntax

• PHP code is enclosed between and .
• One or more code blocks may be embedded in an HTML file.
• Function names are not case-sensitive, but variable names are.

PHP Code Blocks in HTML

• PHP can be embedded within HTML.

PHP Comments

• Single-line comments use "// comment here" or "# comment here".
• Multi-line comments use "/* multiple lines of comments here */".
• You can use comments to explain code logic or disable code segments.

PHP Case Sensitivity

• Keywords (if, else, while, echo, etc.), classes, functions, and user-defined functions are NOT case-sensitive.
• Variable names are case-sensitive.

PHP Variables

• Start with a $ sign, such as $x = 5; or $y = "John";
• Variable names must start with a letters or underscore and can only contain alpha-numeric characters and underscores.
• PHP does not need a command to declare variables; they are created upon initial assignment.

Data Typing

• PHP automatically sets a data type to a variable based on its value.
• Using PHP7 there is the option to type the variable, and declare which datatype is expected.

Examples of variable types

• $x = 5; // $x is an integer
• $y = "John"; // $y is a string
• echo $x;
• echo $y;
• The Data Types that PHP supports include: String, Integer, Float, Boolean, Array, Object, NULL, and Resource

PHP Data Types

• Strings: Represented as text in quotes ("Hello World").
• Integers: Represented as non-decimal numbers.
• Floats (Doubles): Represented with decimals.
• Booleans: Represented with true or false values.
• Arrays: Represented as collections of values in one variable.
• Objects: Represented as a hold for data and methods related to that data.
• NULL: A variable with no value assigned.
• Resources: Represented as special references (e.g., database connections).

Variable Scope

• Variables in PHP can be delcared anywhere on a script.
• Variable scope refers to the section of the script from where the variable can be used.
  • Local: Only assessable within a function.
  • Global: A variable declared outside a function.
    • Using x within a function will generate an error.
  • Static Scope

The global Keyword

• Used to access a global variable from within a function, using global before the variables (inside the function).
• PHP stores all global variables using $GLOBALS[index], the index holds its' name. The array can update variables directly.

PHP Echo/Print

• Echo: Outputs one or more strings; does not return a value, and can handle multiple comma separated parameters.
• Print: Outputs one string, always returns 1, and is slightly slower than echo.

Control Structures

• Control structures alter the default order of execution.
  • Conditionals: (if and switch) execute/skip statements based on an expression.
  • Loops: (while and for) repeatedly execute statements.
  • Jumps: (break, return, and throw) cause the interpreter to jump to another part of the program.

Conditionals in PHP

• Conditionals perform actions based on "if", "else" and "else if" parameters.

Loops in PHP

• PHP has a number of built in loops:
  • For: loops through a block of code a set number of times
  • While: loops through a block of code while a set condition is true
  • Do/While: loops through a block of code once before checking to see if the condition is true

For Loop syntax

• For: loops through a block of code a set number of times
• for (initialization; condition; increment/decrement) { // code block to execute. }

While Loop syntax

• While: loops through a block of code while a set condition is true
• while (condition) { // code block to execute. }

Do...While Loop syntax

• Do/While: loops through a block of code once before checking to see if the condition is true
• while (condition) { // code block to execute. }

PHP Strings

• PHP strings are surrounded by either single/double quotation marks.
• Double quotes perform operations for special characters: example:
  • $x = "John";
  • echo "Hello $x";
• Single quotes do not perform operations, so variable names are returned as written.

String Functions in PHP

• strlen(): Returns the length of a string. Example: echo strlen("Hello world!"); returns //12
• str_word_count(): Counts the words in a string. Example: echo str_word_count("Hello world!"); returns //2
• strpos(): Searches a text within a string. Upon finding a match, the character postion of the first match is returned. Example: echo strpos("Hello world!", "world"); returns //6

PHP - Modify Strings

• strtoupper() : The string is returned in uppercase. To use this function $x = "Hello World!"; followed by echo strtoupper($x);
• strtolower() : The string is returned in lowercase. To use this function $x = "Hello World!"; followed by echo strtolower($x);
• str_replace() : The function replaces characters in the string. To use this function $x = "Hello World!";; Followed by echo str_replace("World", "Dolly", $x);
• strrev(): The function reverses a string. $x = "Hello World!"; followed by echo strrev($x).
• trim(): Any whitespace at the start and end is removed. $x = " Hello World! "; followed by echo trim($x);
• explode(): The function splits a string into an array. The first parameter in explode() represents the "seperator". To use the function: $x = "Hello World!"; followed by the code $y = explode(" ", $x);

PHP Casting

• Ensure data is treated as the intended type; used when mixing data from forms, URLs, or text to numeric operations.
• Cast Syntax: (int) $variable, (float) $variable, (bool) $variable, etc.
• Example:

PHP Constants

• A constant's value cannot be changed during the script.
• Valid constant names must start with a letter or underscore (without a $ sign).
• Constants are automatically global across the script.
• To create a constant use define().
  • define(name, value);
  • define("ROOT_LOCATION", "/usr/local/www/");
• To display use: $directory = ROOT_LOCATION;

Example of PHP Constants

• constants are global and can be used throughout the whole script. define("GREETING", "Welcome to W3Schools.com!"); function myTest() { echo GREETING; } myTest();

PHP Magic Constants

__LINE__ : Current line number. __FILE__ : Full path and filename. __DIR__ : Directory of the file. __FUNCTION__,__CLASS__,__METHOD__,__NAMESPACE__.

PHP Functions

• PHP has more than 1000 built in functions that can be modified.
• A function is a block of statements that can be used repeatedly in a program, however the functions will not run unless it is activated.
• A function will be executed by a call to the function.
• A user-defined function word function, followed by the word echo "$fname Refsnes.";

Passing arguments to functions

• Passing by value is used ,and the orginal variables value is not changed if the recipient variable is changed.
• Passing by reference, appends an ampersand(&) to the front of the parameter(s). Any changes made to a variable passed by refernce change the original version.

Default and Optional arguments

• Default values can input during the declarations of arguments. The value will automatically be assigned if not declared for a particular parameter
• Arguments are designated options as long as they are made the end of the list and assigned to a default value of "nothing".
• Example: function salestax($price,$tax="")

Various Arguments.

• functions use three dots in front of functions to accept an unknown number arguments.
• This type of function is called a variadic function and becomes an array
• Only one variable with this variable can be used at a time and must be the last argument.

PHP 7 Declarations

• An option to specify the expected data type when declare a function.
• When the strict declarations are specified, if PHP sees different data type, a fatal error will appear.
• To use declaration: <?php declare(strict_types=1); function addNumbers (int a, int b)

Arrays

• Arrays store more than a single value.
• Arrays ca nbe made informally, simply by making its data by referencing it $state[0] = "Delaware";
• Arrays can be created formally by using the array() function array array([item1 [,item2 ... [,itemN]]]) $languages = array ("English", "Gaelic", "Spanish");

Indexed arrays

• arrays can use numerical values for reference
• Two ways this can be done:
  • $cars = array("Volvo", "BMW", "Toyota"); or
  • $cars[0] = "Volvo";
  • $cars[1] = "BMW";
  • $cars[2] = "Toyota"

Associative Arrays

• Associative arrays assign the keys.
• There are two ways that can set up the key's:
  • $age = array("Peter"=>"35", "Ben"=>"37", "Joe"=>"43"); OR
  • $age['Peter'] = "35";
  • $age['Ben'] = "37";
  • $age['Joe'] = "43";

Array functions

• Range(): function provides a way to to fill the array consisting of range of values:
  • $die = range(0,6);
  • $even = range(0,20,2);
  • $letters = range("A","F")

How to Output Arrays

• print_r() Is used to show the code of arrays and objects in formatted form to read.
• To use the command: <?php $fruits = array ("Value", "Value2); print_r($fruits);

How to add and remove array elements

• array_push() The array_push() function adds variable onto the end of the target array. Example: $states = array=("Valuet", "Value2); array_push($states,"California","Texas").

array_pop() function

• Returns the element from the target array. Example: $states = array("Valuet"."Name", Secondname): $state=array_pop($states):

Array Shift

• array_shift() The array_shift() function can be similar to array_pop- the differnece, it will return the first item it finds in the target array.

• Array unshift Array is similar in the way array_push () works. However it adds elements to the top of the array instead of top of the array. $states = array("Secondname"."Name"):

Array_unshift ($states, Cailifornia, second Name).

Array-pad () function

• array_pad() is used to modify an array by changing the length by adding a variable to the beginning or the end. array_pad ($array; $size; $value).

Syntax for locating array elements.

• array-keys () Returns all the keys located the array
• Synatx array_Keys(array; search- value, $, strict) Array - the input array Search_Value the optional value. If the the provided array. Keys. Will only the provide, the key of the mathing elements in the array. ###array Key- exists Determines if the specified indicator occurs to the arrary

array intersect is used to array, and it returns (false) otherwise. The value array Key (_ exists S key to check, $ array Name); array Key ( "key",$ is fruit the ///.

array intersect) is used to find the common values in one array,