PHP Data Types

PHP has a total of eight data types which we use to construct our variables:

Integers:
Are whole numbers, without a decimal point, like 4195.They are whole numbers, without a decimal point, like 4195. They are the simplest type .they correspond to simple whole numbers, both positive and negative. Integers can be assigned to variables, or they can be used in expressions, like so:

$int_var = 12345;
$another_int = -12345 + 12345;

Doubles: 
Are floating-point numbers, like 3.14159 or 49.1. They like 3.14159 or 49.1. By default, doubles print with the minimum number of decimal places needed. For example, the code:

$many = 2.2888800;
$many_2 = 2.2111200;
$few = $many + $many_2;
print(.$many + $many_2 = $few<br>.);
It produces the following browser output:

2.28888 + 2.21112 = 4.5

Booleans: 
Have only two possible values either true or false. They have only two possible values either true or false. PHP provides a couple of constants especially for use as Booleans: TRUE and FALSE, which can be used like so:

if (TRUE)
   print("This will always print<br>");
else
   print("This will never print<br>");

NULL: 
Is a special type that only has one value: NULL. NULL is a special type that only has one value: NULL. To give a variable the NULL value, simply assign it like this:

$my_var = NULL;
The special constant NULL is capitalized by convention, but actually it is case insensitive; you could just as well have typed:

$my_var = null;
A variable that has been assigned NULL has the following properties:

It evaluates to FALSE in a Boolean context.

It returns FALSE when tested with IsSet() function.

Strings:
Are sequences of characters, like 'PHP supports string operations. They are sequences of characters, like "PHP supports string operations". Following are valid examples of string

$string_1 = "This is a string in double quotes";
$string_2 = "This is a somewhat longer, singly quoted string";
$string_39 = "This string has thirty-nine characters";
$string_0 = ""; // a string with zero characters

Arrays: 
Are named and indexed collections of other values.

Objects: 
Are instances of programmer-defined classes, which can package up both other kinds of values and functions that are specific to the class.

Resources: 
Are special variables that hold references to resources external to PHP (such as database connections).