Introduction To PHP



History

Developed by Rasmus Lerdore in the year 1994, use for monitor his online resume and personal information.
It was called ' Personal Home Page ' but he renamed as ' Hyper Text Pre-Processor '.

 
Introduction Of PHP

PHP stands for (Hyper Text Pre-Processor). PHP is fully open source. PHP is a server side scripting language that is embedded with HTML(Hyper Text Markup Language). The syntax of PHP is C-Like.
PHP are highly used in modern world. PHP is used in website, application, etc. PHP is a popular language. PHP integrate large number of database like-MySQL, PostgreSQL, Sybase, Oracle, etc. 

Characterstics Of PHP

The most common characterstics of php are as follow :

- Simplicity
- Security
- Efficency
- Familiarity
- Flexibility

Uses Of PHP

The following uses of php are as :-

1) PHP perform many system function like:- create,open, read, write and close.

2) PHP maintain form means, retrive data, send data, etc.

3) Using PHP you can add, delete, update information from database.

4) Using PHP you can access cookies variable and set cookies.

5) Using PHP you can encrypt data.

Hello World In PHP

The Hello World program in php as:
<html>
   <head>
     <title> Hello World Program </title>
  </head>
  <body>
      <?php
        echo " Hello World ";
       ?>
  </body>
</html

PHP Is Case Sensitive

The php is case sensitive language. For Example :-
<html>
  <head>
     <title> Example to show php is case sensitive</title>
  </head>
  <body>
    <?php
       $value = 55;
       print("Value is = $value<br>");
       print("value is = $Value<br>");

    ?> 
  </body>
</html>

OUTPUT :
Value is = 55
value is = 

PHP Data Type

In php there are many data type which are as follow:

1) Integer : - Integer are number Like : - 255, 34, etc. Integer are not a decimal value.

2) Double : - Double are float number or decimal value Like : - 3.4, 12.5, etc.

3) Boolean : - Boolean values are either True or False.

4) Null : - In php null is the special type of data type whose value is only Null.

5) String : - String in php are sequence of characters Like:- " Ram is good boy ".

6) Array : - In php array are the indexed and name collection of vlaue.

7) Object : - In php object are the instance of variabe. Object are the run time entity.

8) Resources : - Resources are special type of data type that hold reference to resource.

PHP Variables

In php variabel are container where value can be store.
eg. : - $var = 56;

Types of Variable are : -

1)  Local Variable
2) Global Variable
3) Static Variable
4) Function Parameters

Variable Naming : -

The following rules for naming variable :
- Variable name must start with letter or underscore.
- Variable consist of number, letters, underscore.
- There is no size limit for variable.
- Variable name must start with $ sign.
eg. : $var = 45;

PHP Constant

In php constant are the name or an identifier for a value. A constant value cannot change during the execution of script. A constant is case-sensitive. Constant identifiers are always in uppercase. A constant name must starts with a letter or underscore, followed by any number of letters, numbers, or underscores.

For use a constant you have to use define() function and to retrieve the value of a constant, simply you specifying its name. Unlike with variables, you do not use to have a constant with a $ sign. 

Please comment for any query.
THANK YOU