Php introduction

PHP Syntax
 A PHP script starts with
<?php
and ends with
?>
<?php
echo "Hello World!";
?>

PHP Variables
 In PHP, a variable starts with the $ sign, followed by the
name of the variable
 <?php
$txt = "Hello world!";
$x = 5;
$y = 10.5;
?>
 Rules for PHP variables:
 A variable starts with the $ sign, followed by the name of the
variable
 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)

PHP echo and print Statements
 echo and print are more or less the
same. They are both used to output data
to the screen.
 The differences are small: echo has no
return value while print has a return
value of 1 so it can be used in
expressions. echo can take multiple
parameters (although such usage is
rare) while print can take one argument.
echo is marginally faster than print.

PHP echo and print Statements
 <?php
$txt1 = "Learn PHP";
$txt2 = "W3Schools.com";
$x = 5;
$y = 4;
echo "<h2>$txt1</h2>";
echo "Study PHP at $txt2<br>";
print($txt2 );
?>

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
 Object
 NULL

PHP String
 <?php
$x = "Hello world!";
$y = 'Hello world!';
echo $x;
echo "<br>";
echo $y;
?>

PHP Integer
 <?php
$x = 5985;
var_dump($x);
?>

PHP Float
 <?php
$x = 10.365;
var_dump($x);
?>

PHP Boolean
 $x = true;
$y = false;

PHP Array
 An array stores multiple values in one
single variable.
 <?php
$cars = array("Volvo","BMW","Toyota");
var_dump($cars);
?>

PHP Object
 $object =
json_decode(json_encode($array),
FALSE);
 $object = (object) $array_name; //now it
is converted to object and you can
access it.
 echo $object->username;

PHP NULL Value
 Null is a special data type which can have only one
value: NULL.
 A variable of data type NULL is a variable that has no
value assigned to it.
 Tip: If a variable is created without a value, it is
automatically assigned a value of NULL.
 Variables can also be emptied by setting the value to
NULL:
 <?php
$x = "Hello world!";
$x = null;
var_dump($x);
?>

PHP Constants
 A constant is an identifier (name) for a
simple value. The value cannot be
changed during the script.
 A valid constant name starts with a letter
or underscore (no $ sign before the
constant name).
 Note: Unlike variables, constants are
automatically global across the entire
script.

PHP Constants
 To create a constant, use the define()
function.
 Syntax :
define(name, value, case-insensitive)
 <?php
define("GREETING", "Welcome to
W3Schools.com!", true);
echo greeting;
?>

PHP 5 Operators
 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

PHP Arithmetic Operators
Operator Name Example Result
+ Addition $x + $y Sum of $x and
$y
- Subtraction $x - $y Difference of $x
and $y
* Multiplication $x * $y Product of $x
and $y
/ Division $x / $y Quotient of $x
and $y
% Modulus $x % $y Remainder of $x
divided by $y
** Exponentiation $x ** $y Result of raising
$x to the $y'th
power
(Introduced in
PHP 5.6)

PHP Assignment Operators
Assignment Same as... Description
x = y x = y The left operand gets
set to the value of the
expression on the
right
x += y x = x + y Addition
x -= y x = x - y Subtraction
x *= y x = x * y Multiplication
x /= y x = x / y Division
x %= y x = x % y Modulus

PHP Comparison Operators
Operator Name Example
== Equal $x == $y
=== Identical $x === $y
!= Not equal $x != $y
<> Not equal $x <> $y
!== Not identical $x !== $y
> Greater than $x > $y
< Less than $x < $y
>= Greater than or equal
to
$x >= $y
<= Less than or equal to $x <= $y

PHP 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.

PHP 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.
Operator Name Description
++$x Pre-increment Increments $x by
one, then returns $x
$x++ Post-increment Returns $x, then
increments $x by one
--$x Pre-decrement Decrements $x by
one, then returns $x
$x-- Post-decrement Returns $x, then
decrements $x by
one

PHP Logical Operators
 The PHP logical operators are used to
combine conditional statements.
and And $x and $y
or Or $x or $y
xor Xor $x xor $y
&& And $x && $y
|| Or $x || $y
! Not !$x

PHP String Operators
 PHP has two operators that are
specially designed for strings.
. Concatenation $txt1 . $txt2
.= Concatenation
assignment
$txt1 .= $txt2

PHP Array Operators
+ Union $x + $y
== Equality $x == $y
=== Identity $x === $y
!= Inequality $x != $y
<> Inequality $x <> $y
!== Non-identity $x !== $y

Php introduction

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Php introduction