PHP Constant


Constants are variables that except once they are defined they cannot be undefined or changed.

A constant is an identifier or a name.
The value cannot be changed during the script.
A valid constant in PHP can be start with letter or underscore.
Create a PHP Constant ?
To create a constant in PHP, use the ‘define ()’ function ‘const’ keyword.
PHP constant using define ()-
Define (name, value)
name: Specifies the name of the constant.
value: Specifies the value of the constant.
Let's see the example to define PHP constant using define().

Output :

PHP constant using, const keyword-
(1) It is bit faster than define().
(2) It is always be case-sensitive.

Let's see the example to define PHP constant using const keyword.

Output :

Note :
Unlike variables, constants are automatically global across the entire script.
PHP echo Statements
echo used to print  output data to the screen.
The PHP echo Statement
The echo statement can be used with or without parentheses: echo or echo().

Output :

Content writer:
Er. Noman Rayeen
CSE 6th Sem

TSPC, Burhanpur
Python Programming ↓ 👆
Java Programming ↓ 👆
JAVA covered following topics in these notes.
JAVA Programs
Principles of Programming Languages ↓ 👆
Principles of Programming Languages covered following topics in these notes.

Previous years solved papers:
A list of Video lectures References:
  1. Sebesta,”Concept of programming Language”, Pearson Edu 
  2. Louden, “Programming Languages: Principles & Practices” , Cengage Learning 
  3. Tucker, “Programming Languages: Principles and paradigms “, Tata McGraw –Hill. 
  4. E Horowitz, "Programming Languages", 2nd Edition, Addison Wesley

    Computer Organization and Architecture ↓ 👆

    Computer Organization and Architecture covered following topics in these notes.

    1. Structure of desktop computers
    2. Logic gates
    3. Register organization
    4. Bus structure
    5. Addressing modes
    6. Register transfer language
    7. Direct mapping numericals
    8. Register in Assembly Language Programming
    9. Arrays in Assembly Language Programming


    1. William stalling ,“Computer Architecture and Organization” PHI
    2. Morris Mano , “Computer System Organization ”PHI

    Computer Network ↓ 👆
    Computer Network covered following topics in these notes.
    1. Data Link Layer
    2. Framing
    3. Byte count framing method
    4. Flag bytes with byte stuffing framing method
    5. Flag bits with bit stuffing framing method
    6. Physical layer coding violations framing method
    7. Error control in data link layer
    8. Stop and Wait scheme
    9. Sliding Window Protocol
    10. One bit sliding window protocol
    11. A protocol Using Go-Back-N
    12. Selective repeat protocol
    13. Application layer
    1. Andrew S. Tanenbaum, David J. Wetherall, “Computer Networks” Pearson Education.
    2. Douglas E Comer, “Internetworking with TCP/IP Principles, Protocols, And Architecture",Pearson Education
    3. KavehPahlavan, Prashant Krishnamurthy, “Networking Fundamentals”, Wiley Publication.
    4. Ying-Dar Lin, Ren-Hung Hwang, Fred Baker, “Computer Networks: An Open Source Approach”, McGraw Hill.