How to Declare Variables in PHP - Informatic Point

How to Declare Variables in PHP

How to declare a variable in PHP. The following article, variables in PHP, gives an outline for the different variables available in PHP. All variable stores some set of information where information is a value. This value of information can be a string, boolean, number, array or it can be an object, and so on.

Declaration of variables in PHP?

The variables declared reserve information. There are several things one necessity to know about representing variables in PHP.

  • Variables represented always begin with a dollar sign ($). A variable name must start each with a letter or an underscore but not with a number.
  • Variables do not carry spaces and these variable names are case-sensitive example $apple is different from $Apple.
  • Variables declaration uses the assignment operator ‘=’ wherein the variable name is on the left side of the operator and the appearance on the right side of the operator.
  • As we understand that PHP is a loosely standardized language, the variables represented do know in advance what type of the variable it will be, meaning that it can be represented as a number or a string or an array or anything else.

How to Initialize Variables in PHP?

From the earlier, we know that PHP language is a loosely typed language and we need not represent the type like whether the variable is of integer, or string or boolean type before using it as it appears in other languages. The type of variable depends upon the value of its repositories. Let us learn through variables in PHP with examples.

Here in the following example, we observe that the height is a float value and the base is an integer value and based on these values we have estimated the area of the triangle.

$height = 15.5;           //float variable
$base = 40;               //integer variable
$area_of_triangle = ($height * $base) / 2;
echo 'The area of triangle is '. $area_of_triangle;
The area of triangle is:310

Types of Variables with Examples

Variables store the values. These values allocated to the variables specify what type of variable it is. There are seven data types listed below:

  1. Integer
  2. String
  3. Array
  4. Boolean
  5. Float
  6. NULL
  7. Object

1. Integer

An integer is a complete number. This integer can be positive or negative. It urgently has at smallest one digit ordering from 0 to 9, with no comma or blanks. It does not have a decimal point. Integers have different notations like

  1. decimal(base 10)
  2. hexadecimal(base 16, prefixed with 0x)
  3. octal(base 8, prefixed with 0)

optionally preceded with a sign either – or +

$x = 700;
$y = 35;
echo '<br>';

2. String

A string is a flow of characters or letters. A string can contain a flow of numbers of arithmetic values also. It can be a sequence of all as well. To represent a string we use single or double quotes.

$input = 'Grape ';
echo '<br> $input is my favorite fruit';
echo "<br> $input is my favorite fruit";
$input is my favorite fruit
Grape is my favorite fruit

3. Array

It is a set of similar and different data types. An array is represented in the form of a key-value pair.

$directions= array('Apple','Orange','Banana','grape');
echo '<br>';
echo $directions[2] echo '<br>';
echo $directions[0];

4. Boolean

This data type can contain one of two values either a true or a false, where true is 1 and false is blank.

$input = true;
echo "<br> True is ".$input;
$input_value = false;
echo "<br> False is ".$input_value;
True is 1
False is

5. Float

A number with a decimal point or using an exponential form is called a floating-point number or is of type float.

$input = 10.45;
$input_value = 5.e5;
echo '<br>';


When no value is specified to a variable and the variable is empty we can use NULL value.

$input = 'The output of demo';
echo '<br/>';
$input = NULL;
string(18) “The output of demo”

7. Object

An object is a data type that stores data. Besides data, it also stores information about the processing of the data. An object is represented explicitly by declaring class variables in PHP. The class is specified with the class PHP keyword. A Class is a structure that holds data members and data methods.

A class is instantiated and the object is formed, and through this object now we can reach the members and methods of the class.

class sub{
public $string = "My favourite sub is Computer";
function display() {
return $this->string;
$object = new sub;
echo $object->string;
My favourite sub is Computer

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