Data-types, Variables and Operators

PHP Data types

A variable can store different types of Data. Let’s have a look at some of the data types supported by PHP:

PHP String

A string is a sequence of characters. In PHP, you can write the string inside single or double quotes.

<?php $a = "Hello World!";

$b = 'Hello World!';

echo $a;

echo "<br>";

echo $b; 

?>

PHP Integer

An integer data type is a non-decimal number between -2,147,483,648 and 2,147,483,647. An integer must have at least one digit and can be either positive or negative.
The following example takes $a as an integer. The PHP var_dump() function returns the data type and value.

<?php 

$a = 0711;

var_dump($a); 

?> 

PHP Float

A float or floating point number is a number with a decimal point or a number in exponential form.

The following example takes $a as a float and the PHP var_dump() function returns the data type and value.

<?php

$a = 14.763;

var_dump($a);

?> 

PHP Boolean

A Boolean represents two possible states: TRUE or FALSE. They are often used in conditional testing.

$a = true;

$b = false;

PHP Object

An object is a data type which stores data and information on how to process that data. In PHP, an object must be explicitly declared. We need to declare a class of object using the class keyword.

<?php

class Student

{

    function Student()

    {

    $this->name = “XYZ”;

    }

}

// create an object

$Daniel = new Student(); // show object properties

echo $Daniel->name; 

?>

PHP Array

An array stores multiple values in one single variable. In the following example, the PHP var_dump() function returns the data type and value.

<?php 

$students = array(“Daniel”,”Josh”,”Sam”);

var_dump($students); 

?>

Now that you have learnt about the various Data Types, let’s move ahead with the PHP Tutorial and have a look at the different PHP Variables. 

PHP Variables

Variables are containers for storing information. All variables in PHP are denoted with a leading dollar sign ($). Unlike other programming languages, PHP has no command for declaring a variable. It is created the moment you first assign a value to it.

Declaring PHP Variables:

<?php

$txt = "Hello World!";

$a = 7;

$b = 11.5; 

?>

The PHP echo statement is often used to output data to the screen.

PHP Variables Scope

In PHP, variables can be declared anywhere in the script. The scope of a variable is the part of the script where the variable can be used.

In PHP we have three different variable scopes:

            1. Local – A variable declared within a function has a LOCAL SCOPE and can only be accessed within that function:

<?php 

    function myTest() 

    { 

    $a = 7; // local scope 

    echo "<p>Variable a inside function is: $a</p>"; 

    } 

    myTest(); // using x outside the function will generate an error echo 

"<p>Variable a outside function is: $a</p>"; 

?>

2. Global– A variable declared outside a function has a GLOBAL SCOPE and can only be accessed outside a function. The global keyword is used to access a global variable from within a function:

<?php

$a = 9; // global scope

function myTest() {

// using a inside this function will generate an error

echo "<p>Variable a inside function is: $a</p>";

}

myTest();

echo "<p>Variable a outside function is: $a</p>"; 

?>

3. Static– When a function is executed, all of its variables are deleted. But if you want any variable not to be deleted, the static keyword is used when you first declare the variable:

<?php

function myTest() 

{

static $a = 0;

echo $a; $a++; 

}

myTest();

myTest();

myTest();

?>

Now that you know about the declaration of variables, let’s move ahead with the PHP Tutorial and have a look at the operators in PHP.

PHP Operators

Operators are used for performing different operations on variables. Let’s have a look at the different operators in PHP:

• Arithmetic operators
• Assignment operators
• Comparison operators
• Logical operators
• Array operators

Arithmetic Operators

The PHP arithmetic operators are used with numeric values to perform common arithmetical operations, such as addition, subtraction, multiplication etc.

Operator	Name	Example	Result
+	Addition	$a + $b	Sum of $a and $b
–	Subtraction	$a – $b	Difference of $a and $b
*	Multiplication	$a * $b	Product of $a and $b
/	Division	$a / $b	Quotient of $a and $b
%	Modulus	$a % $b	Remainder of $a divided by $b
**	Exponentiation	$a ** $b	Result of raising $a to the $b’th power

 

Assignment Operators

The PHP assignment operators are used with numeric values to write a value to a variable.

Assignment	Similar to	Result
a = b	a = b	The left operand gets set to the value of the expression on the right.
a += b	a = a + b	Addition
a -= b	a = a – b	Subtraction

 

Comparison Operators

The PHP comparison operators are used to compare two numbers or strings

Operator	Name	Example
==	Equal	$a == $b
===	Identical	$a === $b
!=	Not equal	$a != $b
<>	Not equal	$a <> $b
!==	Not identical	$a !== $b
>	Greater than	$a > $b
<	Less than	$a < $b
>=	Greater than or equal to	$a >= $b
<=	Less than or equal to	$a <= $b

 

Logical Operators

The PHP logical operators are used to combine conditional statements.

Operator	Name	Example
and	And	True if both $a & $b are true
or	Or	True if either $a or $b are true
xor	Xor	True if either $a or $b are true, but not both
&&	And	True if both $a & $b are true
||	Or	True if either $a or $b are true
!	Not	True if $a is not true

 

Array Operators

The PHP array operators are used to compare arrays.

Operator	Name	Example
+	Union	$a + $b
==	Equality	$a == $b
===	Identity	$a === $b
!=	Inequality	$a != $b
<>	Inequality	$a <> $b
!==	Non-identity	$a !== $b

 Now let’s move ahead with our PHP Tutorial and have a look at the various OOP concepts in PHP.