Explain PHP data types and keywords in PHP

PHP data types are used to hold different types of data or values. PHP supports 8 primitive data types that can be categorised further in 3 types:

1. Scalar Types (predefined)
2. Compound Types (user-defined)
3. Special Types

Scalar Types

Boolean

++ It is often used with conditional statements. If the condition is correct, it returns TRUE otherwise FALSE.

Example:

<?php   

    if (TRUE)  

        echo “This condition is TRUE.”;  

    if (FALSE)  

        echo “This condition is FALSE.”;  

?>  

Integer

Integer means numeric data with a negative or positive sign. It holds only whole numbers, i.e., numbers without fractional parts or decimal points.

Rules for integer:

• An integer can be either positive or negative.
• An integer must not contain a decimal point.
• Integers can be decimal (base 10), octal (base 8), or hexadecimal (base 16).
• The range of an integer must lie between 2,147,483,648 and 2,147,483,647 i.e., -2^31 to 2^31.

Example:

<?php   

    $dec1 = 34;  

    $oct1 = 0243;  

    $hexa1 = 0x45;  

    echo “Decimal number: ” .$dec1. “</br>”;  

    echo “Octal number: ” .$oct1. “</br>”;  

    echo “HexaDecimal number: ” .$hexa1. “</br>”;  

?>  

Float

A floating-point number is a number with a decimal point. Unlike integers, it can hold numbers with a fractional or decimal point, including a negative or positive sign.

Example:

<?php   

    $n1 = 19.34;  

    $n2 = 54.472;  

    $sum = $n1 + $n2;  

    echo “Addition of floating numbers: ” .$sum;  

?> 

String

A string is a non-numeric data type. It holds letters or any alphabets, numbers, and even special characters. String values must be enclosed either within single quotes or in double quotes. But both are treated differently. To clarify this, see the example below:

<?php   

    $company = “Javatpoint”;  

    echo “Hello $company”;  

  ?>  

Compound Types

Array

An array is a compound data type. It can store multiple values of the same data type in a single variable.

Example:

<?php   

    $bikes = array (“Royal Enfield”, “Yamaha”, “KTM”);  

    var_dump($bikes);   //the var_dump() function returns the data type and values  

    echo “</br>”;  

    echo “Array Element1: $bikes[0] </br>”;  

    echo “Array Element2: $bikes[1] </br>”;  

    echo “Array Element3: $bikes[2] </br>”;  

?>

Object

Objects are the instances of user-defined classes that can store both values and functions. They must be explicitly declared.

Example:

<?php   

     class bike {  

          function model() {  

               $model_name = “Royal Enfield”;  

               echo “Bike Model: ” .$model_name;  

             }  

     }  

     $obj = new bike();  

     $obj -> model();  

?>

Special Types

Resource

Resources are not the exact data type in PHP. Basically, these are used to store some function calls or references to external PHP resources. For example – a database call. It is an external resource.

Null

Null is a special data type that has only one value: NULL. There is a convention of writing it in capital letters as it is case sensitive.

The special type of data type NULL defines a variable with no value.