PHP Data types


Data Types: Data types defines the type of values a variable can store.

PHP supports the following data types:
·         String
·         Integer
·         Float (floating point numbers - also called double)
·         Boolean
·         Array
·         Object
·         NULL

String : A string is a collection of characters, like "Hi guys".
We use quotes(" ") to define a string. We can use single or double quotes:

$q = "Hi guys !";
$w = 'Keep smiling';
echo $q;
echo "
echo $w;

Hi guys!
Keep smiling

Integer: An integer data type is a non-decimal number between -2,147,483,648 and 2,147,483,647.It stores integer type of values.

Rules for integers:
·         An integer must have at least one digit
·         An integer must not have a decimal point
·         An integer can be either positive or negative

$a= 57

In the above $a is an integer. The PHP var_dump() function returns the data type and value:

Float: A float (floating point number) is a  number in the exponential form.
In the following example $x is a float. The PHP var_dump() function returns the data type and value:

$x = 1.35;


Boolean: A Boolean represents two possible states: TRUE or FALSE.
$A = true;
$B = false;
Booleans are used for conditional testing.

Array: An array is a type of container that stores multiple values in one single variable in contigous memory allocation.

$flower = array("Lilly","Rose","Lotus");

array(3) { [0]=> string(5) "Lilly" [1]=> string(3) "Rose" [2]=> string(6) "Lotus" }
In the above example $flower is an array. The PHP var_dump() function returns the data type and value.

Object: An object is a data type which stores data and information on how to process that data.
Object is an entity that reflects real world objects.

Rules to declare Object:
·         In PHP, an object must be explicitly declared.
·         we must declare a class of object. For this, we use the class keyword. A class is a structure that can contain properties and methods.

class Flower{
function Flower() {
    $this->model = "Lotus";
// create an object
$obj = new Flower();
// show object properties
echo $obj->model;


NULL Value: Null is a special data type which can have only one value: NULL.
A variable of data type NULL is a variable that has no value assigned to it.
By default, a variable is of NULL data type if no value is assigned to it.
Variables can also be emptied by setting the value to NULL

$a = "Hi guys!";
$a = null;


Content writer:
Er. Khushi Jain
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.