PHP Variables

VARIABLES IN PHP

Variables are like a container to store data.
Variables in php starts with Dollar sign ($).

Example:
$a = "Hello";
$b = 50;
$c = 10.50;
?>

OUTPUT:
Hello
50
10.50

In the above example , there are 3 variables a,b,c which holds values "Hello","50" and"10.50" respectively.

Rules to declare a variable:
·         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 alphanumeric characters and underscores (A-z, 0-9, and _ )
·         Variable names are case-sensitive ($age and $AGE are two different variables)

Since php is a case-sensitive language make sure that your variables are properly used.

Printing the variable:
We use 'echo' or 'print' keyword to print a variable.

Example:
$a = "professorjayesh.com";
echo " This is $a";
?>

Scope of Variable:
PHP has three different variable scopes:
·         local
·         global
·         static
Global Variable: - A variable declared outside a function has a GLOBAL SCOPE and can only be accessed outside a function:

Example :
$a = 10; // global scope
function fun() {
   // using x inside this function will generate an error
   echo "Variable a in the function is: $a
";
}
fun();
echo "Variable a outside function is: $a
";
?>

OUTPUT :
Variable a in the function is:
Variable a outside function is: 50
LOCAL VARIABLE : A variable declared within a function has a LOCAL SCOPE and can only be accessed within that function:

Example
function fun() {
   $a = "Hii.."; // local scope
   echo "Variable a in the function is: $a
";
}
fun();
// using a outside the function will generate an error
echo "Variable a outside function is: $a
";
?>

OUTPUT :
Variable a inside function is: Hii..
Variable a outside function is:


Content writer:
Er. Khushi Jain
CSE 6th Sem

TSPC, Burhanpur

Python Programming ↓ 👆
Java Programming ↓ 👆
JAVA EasyExamNotes.com covered following topics in these notes.
JAVA Programs
Principles of Programming Languages ↓ 👆
Principles of Programming Languages
EasyExamNotes.com covered following topics in these notes.

Practicals:
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 

    EasyExamNotes.com 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

    References:

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

    Computer Network ↓ 👆
    Computer Network

    EasyExamNotes.com 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
    References:
    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.