PHP Note One (Systax/variables/echo/print/data Type)

PHP stands for "Hypertext Preprocessor", it is a server scripting language.

What Can PHP do?

• PHP can generate dynamic page content
• PHP can create, open, read, write, delete, and close files on the server
• PHP can collect form data
• PHP can send and receive cookies
• PHP can add, delete, modify data in your database
• PHP can is used to control user-access
• PHP can encrypt data

1> Basic PHP Syntax

1 <? PHP 2 // PHP code goes here 3 ?>

2> Comments in PHP

1<?PHP2 //This is a single-line comment3 4 #This is also a single-line comment5 6 /*7 This is a multiple-lines comment block8 That spans over multiple9 LinesTen */ One  A //You can also use comments to leave out parts of a code line - $x= 5/*+*/+ 5; - Echo $x; the?>

3> Case Sensitivity

In PHP, any keywords (e.g. if, else, while, echo, etc), classes, functions, and user-defined functions is not case- Sensitive.

1 <? PHP 2 ECHO "Hello world!<br>"; 3 Echo "Hello world!<br>"; 4 EcHo "Hello world!<br>"; 5 ?>

however; All variable names is case-sensitive.

1 <? PHP 2 $color = "Red"; 3 Echo $color . "<br>"; 4 Echo $COLOR . "<br>"; 5 Echo $coLOR . "<br>"; 6 ?>

4> PHP Variables

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 is case-sensitive ($age and $AGE are, different variables)

PHP is a loosely Typed Language

PHP Variables Scope

PHP has three different variable scopes:

• Local
• Global
• Static

PHP also stores all global variables in an array called $GLOBALS [index]. The index holds the name of the variable.

1<?PHP2 $x= 5;3 $y= 10;4 5 functionmyTest () {6     $GLOBALS[' y '] =$GLOBALS[' X '] +$GLOBALS[' Y '];7 }8 9 myTest ();Ten Echo $y;//outputs One?>

5> PHP Echo and Print statements

Echo and print is more or less the same. They is both used to output data to the screen.

The differences is small:

• echo have no return value while print have a return value of 1 so it can be used in expressions.
• Echo can take multiple parameters (although such usage are rare) while the print can take one argument.
• Echo is marginally faster than print.

Echo Display Text

1 <? PHP 2 Echo "; 3 Echo "Hello world!<br>"; 4 Echo "I ' m about to learn Php!<br>"; 5 Echo "This", "string", "is", "made", "with multiple parameters." ; 6

Echo Display Variables

1<?PHP2 $txt 1= "Learn PHP";3 $txt 2= "W3schools.com";4 $x= 5;5 $y= 4;6 7 Echo"$txt 1;8 Echo"Study PHP at$txt 2<br> ";9 Echo $x+$y;Ten?>

Print Display Text

1 <? PHP 2 Print "; 3 Print "Hello world!<br>"; 4 Print "I ' m about to learn php!" ; 5 ?>

Print Display Variables

1<?PHP2 $txt 1= "Learn PHP";3 $txt 2= "W3schools.com";4 $x= 5;5 $y= 4;6 7 Print"$txt 1;8 Print"Study PHP at$txt 2<br> ";9 Print $x+$y;Ten?>

6> 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
• Resource

Example

1  <? php  2   $x  = "Hello world!"  3   $y  = 5985  4   $z  = 10.365  5   $cars  = array  ("Volvo", "BMW", "Toyota"  6   var _dump () function returns the data type and value  7  var_dump  ( $cars ); 
8 $a = null;

Object Example

1<?PHP2 classCar {3     functionCar () {4         $this->model = "VW";5     }6 }7 8 //Create an Object9 $herbie=NewCar ();Ten  One //Show Object Properties A Echo $herbie-model; -?>

PHP Note One (Systax/variables/echo/print/data Type)