Php intro by sami kz

Personal Home Page (Old)
Hypertext Preprocessor (Now)
By: @sami_Khan

What is PHP……?
PHP is a server scripting language, and a powerful tool
for making dynamic and interactive Web pages.
PHP is a widely-used, free, and efficient alternative to
competitors such as Microsoft's ASP.

Lecture#2
Download XAMPP: https://www.apachefriends.org/index.html

 Install XAMPP
 Start Apache Server and MySQL

 To Check that Apache server is running or not, we type
in Browser: http://localhost/
 XAMPP page should be opened
 Select language as English

Notepad
Notepad++
Dreamweaver

Notepad
 Notepad is an Application in windows
 Path in Windows 8:
C:UsersManiAppDataRoamingMicrosoftWindowsStart
MenuProgramsAccessories
 Path in Windows 7
C:Windowssystem32
Start Menu:
Start > Programs > Accessories > Notepad

Notepad++
 Download Link:
https://notepad-plus-plus.org/download/v6.8.3.html

Adobe Dreamweaver
 Best Software for scripting
 Easy in use

PHP Syntax
Comment in PHP
Echo/Print

PHP Syntax
 Basic tags of PHP in which we type the whole code of
php.
Syntax:
<?php
// PHP code goes here
?>

PHP Coding
 During PHP coding we also need HTML, so normally we
use HTML & PHP together, (PHP in between HTML).

Comment in PHP
 In large programs we have to use ‘comments’, to
explain next code.
 In PHP we use
 // For One Whole Line
 # For One Whole Line
 /* For Multiple Lines
---
---
*/

Echo/Print
 The echo/print function outputs one or more strings
 The echo function is slightly faster than print
Echo Syntax:
<?php
echo "Hello world!";
?>
Print Syntax:
<?php
print "Hello world!";
?>

echo “string”;
 String must be in double coats
 Semicolon ‘ ; ’ is used to end the line
PHP Code:
<?php
echo “I love Islam”;
?>

Rules for PHP variables:
 A variable defines with the $ (dollar sign)
 A variable name must start with a letter or the underscore
character
 A variable name cannot start with a number
 A variable name can only contain alpha-numeric characters
and underscores (A-z, 0-9, and _ )
 Variable names are case-sensitive ($age and $Age are two
different variables)

Define a Variable
 Variable defines with ‘$’ (dollar sign):
$variable=value;
Example:
<?php
$txt = "Hello world!"; /* String Variable */
$x =35;
$y = 33.5;
?>
Note: When you assign a text value to a variable, put quotes around the value

Output Variables
 The PHP echo statement is often used to output data
to the screen.
 The following example will show how to output text
and a variable:
PHP Code:
<?php
$txt = “Islam";
echo "I love $txt";
?>

Scope of Variables
 In PHP, variables can be declared anywhere in the script.
 The scope of a variable is the part of the script where the
variable can be referenced/used.
 PHP has three different variable scopes:
 Global Variable: A variable declared outside a function has a GLOBAL SCOPE
and can only be accessed outside a function
 Local Variable: A variable declared within a function has a LOCAL SCOPE
and can only be accessed within that function
 Static Variable: when a function is completed/executed, its variables are
deleted. Sometimes we want a local variable.
We use the static keyword when you first declare the variable
static $x = 0;

PHP Data Types
Variables can store data of different types, and different
data types can do different things.
PHP supports the following data types:
 String
 Integer
 Float (floating point numbers - also called double)
 Boolean
 Array

String
 A string is a sequence of characters, like "Hello world!".
 A string can be any text inside quotes. You can use single or
double quotes:

Integer
An integer is a whole number (without decimals). It is a number
between -2,147,483,648 and +2,147,483,647.
Rules for integers:
 An integer must have at least one digit (0-9)
 An integer cannot contain comma or blanks
 An integer must not have a decimal point
 An integer can be either positive or negative
 Integers can be specified in three formats: decimal (10-based),
hexadecimal (16-based - prefixed with 0x) or octal (8-based -
prefixed with 0)

In the following example $x is an integer. The PHP var_dump()
function returns the data type and value:

Float
 A float (floating point number) is a number with a decimal
point or a number in exponential form.
 In the following example $x is a float. The PHP var_dump()

Boolean
A Boolean represents two possible states: TRUE or FALSE.
$x = true;
$y = false;
Booleans are often used in conditional testing. You will
learn more about conditional testing in a later chapter of
this tutorial.

Array
 An array stores multiple values in one single variable.
 In the following example $cars is an array. The PHP var_dump()

PHP String Functions
 strlen() function returns the length of a string.
 str_word_count() function counts the number of words in a
string:
 strrev() function reverses a string:
 strpos() function searches for a specific text within a string.
The function returns the character position of the first match.
 str_replace() function replaces some characters with some
other characters in a string

PHP Constants
 To create a constant, use the define() function.
define(name, value, case-insensitive)
Parameters:
 name: Specifies the name of the constant
 value: Specifies the value of the constant
 case-insensitive: Specifies whether the constant name should be
case-insensitive. Default is false

Constants are Global
 Constants are automatically global and can be used across the
entire script.
The example below uses a constant inside a function, but it is
defined outside the function:
<?php
function myTest() {
echo GREETING;
}
myTest();
?>

PHP Operators
 Operators are used to perform operations on variables and
values.
PHP divides the operators in the following groups:
 Arithmetic operators
 Assignment operators
 Comparison operators
 Increment/Decrement operators
 Logical operators
 String operators
 Array operators

Arithmetic Operators
 The PHP arithmetic operators are used with numeric values to
perform common arithmetical operations, such as addition,
subtraction, multiplication etc.

Assignment Operators
 The PHP assignment operators are used with numeric values
to write a value to a variable.
 The basic assignment operator in PHP is "=". It means that the
left operand gets set to the value of the assignment expression
on the right.

Comparison Operators
The PHP comparison operators are used to compare two values
(number or string):

Increment / Decrement Operators
 The PHP increment operators are used to increment a
variable's value.
 The PHP decrement operators are used to decrement a
variable's value.

Logical Operators
 The PHP logical operators are used to combine conditional
statements.

String Operators
 PHP has two operators that are specially designed for strings.

Array Operators
 The PHP array operators are used to compare arrays.

Conditional Statements
Very often when you write code, you want to perform different
actions for different decisions. You can use conditional
statements in your code to do this.
 In PHP we have the following conditional statements:
 if statement - executes some code only if a specified condition is
true
 if...else statement - executes some code if a condition is true and
another code if the condition is false
 if...elseif....else statement - specifies a new condition to test, if the
first condition is false
 switch statement - selects one of many blocks of code to be
executed

The if Statement
The if statement is used to execute some code only if a
specified condition is true.
Syntax:
if (condition)
{
code to be executed if condition is true;
}

if statement:
<?php
$t = date("H");
if ($t < "20")
{
echo "Have a good day!";
}
?>

The if...else Statement
Use the if....else statement to execute some code if a condition
is true and another code if the condition is false.
Syntax:
if (condition)
{
}
else
{
code to be executed if condition is false;
}

The if...elseif....else Statement
Use the if....elseif...else statement to specify a new condition to
test, if the first condition is false.
Syntax:
if (condition) {
}
elseif (condition) {
}
else {
code to be executed if condition is false;
}

PHP switch Statement
Use the switch statement to select one of many blocks of code
to be executed.
Syntax:
switch (n) {
case label1:
code to be executed if n=label1;
break;
case label2:
break;
case label3:
break;
...
default:
code to be executed if n is different from all labels;
}
Note: Use break to prevent the code from running into the next case automatically.

PHP Loops
Instead of adding several almost equal code-lines in a script, we can
use loops to perform a task like this.
In PHP, we have the following looping statements:
 while - loops through a block of code as long as the specified
condition is true
 do...while - loops through a block of code once, and then repeats
the loop as long as the specified condition is true
 for - loops through a block of code a specified number of times
 foreach - loops through a block of code for each element in an
array

While Loop
The while loop executes a block of code as long as the
Syntax:
while (condition is true)
{
code to be executed;
}

Do...While Loop
The Do...While loop will always execute the block of code once,
it will then check the condition, and repeat the loop while the
Syntax:
Do
{
}
while (condition is true);

For Loop
The for loop is used when you know in advance how many times
the script should run.
Syntax:
for (init counter; test counter; increment counter)
{
}
Parameters:
init counter: Initialize the loop counter value
test counter: Evaluated for each loop iteration. If it evaluates to TRUE, the loop
continues. If it evaluates to FALSE, the loop ends.
increment counter: Increases the loop counter value

The example below displays the numbers from 0 to 10:

Foreach Loop
The foreach loop works only on arrays, and is used to loop
through each key/value pair in an array.
Syntax:
foreach ($array as $value)
{
}
For every loop iteration, the value of the current array element is assigned
to $value and the array pointer is moved by one, until it reaches the last
array element.

The real power of PHP comes from its functions; it has
more than 1000 built-in functions.

Functions in PHP
 A function is a block of statements that can be used
repeatedly in a program.
 A function will not execute immediately when a page
loads.
 A function will be executed by a call to the function.

User Defined Function in PHP
A user defined function declaration starts with the word
"function":
Syntax:
function functionName()
{
}
Note:
 A function name can start with a letter or underscore (not a number).
 Give the function a name that reflects what the function does!
 Function names are NOT case-sensitive.

// Calling a Function
// Creating a Function

Function Arguments
* Default Argument Values

Functions - Returning values
To let a function return a value, use the return statement:
<?php
function sum($x, $y)
{
$z = $x + $y;
return $z;
}
echo "5 + 10 = " . sum(5,10) . "<br>";
echo "7 + 13 = " . sum(7,13) . "<br>";
echo "2 + 4 = " . sum(2,4);
?>

Some Built-in Functions in PHP
Rais-to-power and Square-root Function:
$a = 3; Results:
$b = 4;
$c = pow($a, 2) + pow($b, 2);
echo “ ’a’ rais to power 2 is ".pow($a, 2); 9
echo “ 'b' rais to power 2 is ".pow($b, 2); 16
echo "C = ".(pow($a, 2) + pow($b, 2)); 25
echo “ Square Root of C is ". sqrt($c); 5

Arrays
An array is a special variable, which can hold many values under a single
name, and you can access the values by referring to an index number.

Create an Array in PHP
In PHP, the array() function is used to create an array:
array();
In PHP, there are three types of arrays:
 Indexed arrays - Arrays with a numeric index
 Associative arrays - Arrays with named keys
 Multidimensional arrays - Arrays containing one or more arrays

Indexed Arrays
There are two ways to create indexed arrays:
The index can be assigned automatically (index always starts at 0), like
this:
$cars = array("Volvo", "BMW", "Toyota");
Or the index can be assigned manually:
$cars[0] = "Volvo";
$cars[1] = "BMW";
$cars[2] = "Toyota";

Example
The following example creates an indexed array named $cars, assigns
three elements to it, and then prints a text containing the array values:

Get The Length of an Array
The count() Function:
The count() function is used to return the length (the
number of elements) of an array:
<?php
echo count($cars);
?>

Loop Through an Indexed Array
To loop through and print all the values of an indexed array,
you could use a for loop, like this:
<?php
$arrlength = count($cars);
for($x = 0; $x < $arrlength; $x++) {
echo $cars[$x];
echo "<br>";
}
?>

Associative Arrays
Associative arrays are arrays that use named keys that
you assign to them.
There are two ways to create an associative array:
Syntax:
<?php
$age = array("Peter"=>"35", "Ben"=>"37", "Joe"=>"43");
echo "Peter is " . $age['Peter'] . " years old.";
?>
Result: Peter is 35 years old.

Loop Through an Associative Array
To loop through and print all the values of an associative array,
you could use a foreach loop, like this:

Sort Functions For Arrays
The elements in an array can be sorted in alphabetical or
numerical order, descending or ascending.
PHP array sort functions:
 sort() - sort arrays in ascending order
 rsort() - sort arrays in descending order
 asort() - sort associative arrays in ascending order, according to the value
 ksort() - sort associative arrays in ascending order, according to the key
 arsort() - sort associative arrays in descending order, according to the value
 krsort() - sort associative arrays in descending order, according to the key

Example:
<?php
sort($cars);
$clength = count($cars);
for($x = 0; $x < $clength; $x++) {
echo $cars[$x];
echo "<br>";
} Result: BMW
?> Toyota
Volvo

PHP Global Variables - Superglobals
Several predefined variables in PHP are "superglobals", which means
that they are always accessible, regardless of scope - and you can
access them from any function, class or file without having to do
anything special.
The PHP superglobal variables are:
 $GLOBALS
 $_SERVER
 $_REQUEST
 $_POST
 $_GET
 $_FILES
 $_ENV
 $_COOKIE
 $_SESSION

$GLOBALS
$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.
Example:
<?php
$x = 75;
$y = 25;
function addition() {
$GLOBALS['z'] = $GLOBALS['x'] + $GLOBALS['y'];
}
addition(); Result: 100
echo $z;
?>

$_SERVER
$_SERVER is a PHP super global variable which holds information
about headers, paths, and script locations.
The example below shows how to use some of the elements in
$_SERVER:

The following table lists the most important elements that can go inside $_SERVER:

$_REQUEST
PHP $_REQUEST is used to collect data after submitting an HTML form.
The example below shows a form with an input field and a submit
button. We point to this file itself for processing form data. Then, we can
use the super global variable $_REQUEST to collect the value of the
input field:

$_POST
PHP $_POST is widely used to collect form data after submitting an
HTML form with method="post". $_POST is also widely used to pass
variables.
<form method="post" action="<?php echo $_SERVER['PHP_SELF'];?>">
Name: <input type="text" name="fname">
<input type="submit">
</form>
<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
// collect value of input field
$name = $_POST['fname'];
if (empty($name)) {
echo "Name is empty";
} else {
echo $name;
}
}
?>

$_GET
PHP $_GET can also be used to collect form data after submitting an
HTML form with method="get".
$_GET can also collect data sent in the URL.
Assume we have an HTML page that contains a hyperlink with
parameters:
<a href="test_get.php?subject=PHP&web=W3schools.com">Test $GET</a>
When a user clicks on the link "Test $GET", the parameters "subject" and
"web" is sent to "test_get.php", and you can then access their values in
"test_get.php" with $_GET.

PHP Form Handling
The PHP superglobals $_GET and $_POST are used to collect
form-data.
Simple HTML Form:
<html>
<body>
<form action="welcome.php" method="post">
Name: <input type="text" name="name"><br>
E-mail: <input type="text" name="email"><br>
<input type="submit">
</form>
</body>
</html>

welcome.php
When the user fills out the form above and clicks the submit
button, the form data is sent for processing to a PHP file named
"welcome.php". The form data is sent with the HTTP POST
method.
<html>
<body>
Welcome <?php echo $_POST["name"]; ?> <br>
Your email address is: <?php echo $_POST["email"]; ?>
</body>
</html>

GET vs. POST
Both GET and POST create an array [array( key => value, …)]. This
array holds key/value pairs, where keys are the names of the
form controls and values are the input data from the user.
 $_GET is an array of variables passed to the current script via the URL
parameters.
Information sent from a form with the GET method is visible to everyone.
 $_POST is an array of variables passed to the current script via the HTTP
POST method.
Information sent from a form with the POST method is invisible to others.
Note: Developers prefer POST for sending form data

Form Validation
Proper validation of form data is important to protect your form from
hackers and spammers!
The validation rules for the form above are as follows:

Form Element
<form method="post" action="<?php echo
htmlspecialchars($_SERVER["PHP_SELF"]);?>">
 The $_SERVER["PHP_SELF"] sends the submitted form data to the page
itself, instead of jumping to a different page.
 The htmlspecialchars() function converts special characters to HTML
entities. This means that it will replace HTML characters like < and > with
< and >. This prevents attackers from exploiting the code by
injecting HTML or Javascript code (Cross-site Scripting attacks) in forms.

PHP Forms - Validate E-mail and URL
Validate Name
$name = test_input($_POST["name"]);
if (!preg_match("/^[a-zA-Z ]*$/",$name)) {
$nameErr = "Only letters and white space allowed";
}
Validate E-mail
$email = test_input($_POST["email"]);
if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
$emailErr = "Invalid email format";
}

If the URL address syntax is not valid, then store an error
message:
Validate URL
$website = test_input($_POST["website"]);
if (!preg_match("/b(?:(?:https?|ftp)://|www.)[-a-z0-
9+&@#/%?=~_|!:,.;]*[-a-z0-9+&@#/%=~_|]/i",$website)) {
$websiteErr = "Invalid URL";
}

•With PHP, you can connect to and manipulate databases.
•MySQL is the most popular database system used with PHP.

What is MySQL?
 MySQL is a database system used on the web
 MySQL is a database system that runs on a server
 MySQL is ideal for both small and large applications
 MySQL is very fast, reliable, and easy to use
 MySQL uses standard SQL
 MySQL compiles on a number of platforms
 MySQL is free to download and use
 MySQL is developed, distributed, and supported by Oracle
Corporation
 MySQL is named after co-founder Monty Widenius's daughter: My

MySQL Database
The data in a MySQL database are stored in tables. A table is a
collection of related data, and it consists of columns and rows.
Databases are useful for storing information categorically. A
company may have a database with the following tables:
 Employees
 Products
 Customers
 Orders
Note:
MySQL is the de-facto standard database system for web sites with
HUGE volumes of both data and end-users (like Facebook, Twitter, and
Wikipedia).

Database Queries
“A query is a question or a request.”
We can query a database for specific information and have a
recordset returned.
Look at the following query (using standard SQL):
SELECT LastName FROM Employees;
The query above selects all the data in the "LastName" column from
the "Employees" table.

Download MySQL Database
If you don't have a PHP server with a MySQL Database, you can
download it for free here: http://www.mysql.com
Look at http://www.mysql.com/customers for an overview of
companies using MySQL.

Php intro by sami kz

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