NTRODUCTION

PHP is Hypertext preprocessor It is a server-side scripting language that is used for web development. It can be easily embedded with HTML files. HTML codes can also be written in a PHP file. The PHP codes are executed on the server-side whereas HTML codes are directly executed on the browser.

Characteristics:

• It is simple, easy and fast
• Flexible
• Open source

1. COMMENTS

• A comment in PHP code is a line that is not executed as a part of the program.
• It makes the code more readable
• our code will neat and clean

Types of Commond

1. Single line comment ( // )
2. Multiple lines comment( /* */ )

2. CONSTANTS

• constants are either identifiers or simple names that can be assigned any fixed values.
• Constant Identifiers should be written in upper case 
• constant is always case-Sensitive
•  It always starts with a letter or underscores, letter, numbers or underscore
• A constant name Must never start with a number

SYNTAX: define(name, value, case_insensitive)

3.ECHO / PRINT

• It has no return value and Print has return value of 1
• It can take multiple PArameters and Print can take only one parameter
• echo is faster than print
• example:

4.DATA TYPE

• String: string is a sequence of characters.
• Integer: it holds only whole numbers including positive and negative numbers, the default base is decimal (base 10).
• Boolean: It is used for conditional testing and hold only two values TRUE and FALSE.
• Array: It contain multiple values of same datatype in single variable
• Object: Objects are defined as instances of user-defined classes that can hold both values and functions and information. objects are explicitly declared and created from the new keyword.
• Null: These are special types of variables that can hold only one value NULL and it is case sensitive, If a variable is created without a value or no value, it is automatically assigned a value of NULL

5.SWITCH

• switch statement is used to execute one statement from multiple conditions
• Each case can have a break statement, which is used to terminate the sequence of statement.
• In switch statement, we can use number, character, string, functions
• Syntax

 switch (n)
 {
  case label1:
    code to be executed if n=label1;
    break;
  case label2:
    code to be executed if n=label2;
    break;
  case label3:
    code to be executed if n=label3;
    break;
    ...
  default:
    code to be executed if n is different from all labels;
 }