Operators in PHP are used to perform different operations on operands. Operators can be categorized in following types :
• Arithmetic operators
• Assignment operators
• Comparison operators
• Increment/Decrement operators
• Logical operators
• String operators
• Array operators

Arithmetic operators : Arithmetic operators are used with numeric values to perform common arithmetical operations, such as addition, subtraction, multiplication etc. Assume variable \$x holds 20 and variable \$y holds 10, then :

Operators Name Description Example
+ Addition Sum of \$x and \$y \$x + \$y =30
- Subtraction Difference of \$x and \$y \$x - \$y = -10
* Multiplication Products of \$x and \$y \$x * \$y = 200
/ Division Quotient of \$x and \$y \$x / \$y = 2
% Modulus Remiander of \$x divided by \$y \$x % \$y = 0
** Exponentiation Result of raising \$x to the \$y'th power \$x ** \$y = 10240000000000

Example :
<?php
\$a = 12;
\$b = 8;
\$c = \$a + \$b;
echo \$c;
?>

Output :
20

Assignment operators : Assignment operators are used with numeric values to write a value to a variable.

Shorthand Expression Description
\$x += \$y \$x = \$x + \$y Addition
\$x -= \$y \$x = \$x - \$y Subtraction
\$x *= \$y \$x = \$x * \$y Multiplication
\$x /= \$y \$x = \$x / \$y Division
\$x %= \$y \$x = \$x % \$y Modulus

Example :
<?php
\$x = 10;
\$y = 5;

\$x += \$y;
echo \$x."<br>";
\$x -= \$y;
echo \$x."<br>";
\$x *= \$y;
echo \$x."<br>";
\$x /= \$y;
echo \$x."<br>";
\$x %= \$y;
echo \$x;
?>

Output :
15
10
50
10
0

Comparison operators : Comparison operators are used in PHP to compare two values (number or string).  Assume variable \$x holds 20 and variable \$y holds 10, then :

Operators Name Description Example
== Equal Returns true if \$x is equal to \$y (\$x == \$y) is false
=== Identical Returns true if \$x is equal to \$y, and they are of the same type (\$x === \$y) is false
!= Not equal Returns true if \$x is not equal to \$y (\$x != \$y) is true
<> Not equal Returns true if \$x is not equal to \$y (\$x <> \$y) is true
!== Not identical Returns true if \$x is not equal to \$y, or they are not of the same type (\$x !== \$y) is true
> Greater than Returns true if \$x is greater than \$y (\$x > \$y) is true
< Less than Returns true if \$x is less than \$y (\$x < \$y) is false
>= Greater than or equal to Returns true if \$x is greater than or equal to \$y (\$x >= \$y) is true
<= Less than or equal to Returns true if \$x is less than or equal to \$y (\$x < \$y) is false

Increment/Decrement operators : In PHP increment operators are used to increment a variable's value and decrement operators are used to decrement a variable's value.

Operator Name Description
++\$x Pre-increment Increments \$x by one, then returns \$x
\$x++ Post-increment Returns \$x, then increments \$x by one
--\$x Pre-decrement Decrements \$x by one, then returns \$x
\$x-- Post-decrement Returns \$x, then decrements \$x by one

Example :
<?php
\$x = 10;
echo ++\$x."<br>";
\$y = 20;
echo \$y++."<br>";
\$a = 15;
echo --\$a."<br>";
\$b = 25;
echo \$b--;
?>

Output :
11
20
14
25

Logical operators : Logical operators are used to combine conditional statements.

Operators Name Expression Description
and And \$x and \$y True if both \$x and \$y are true
or Or \$x or \$y True if either \$x or \$y is true
xor Xor \$x xor \$y True if either \$x or \$y is true, but not both
&& And \$x && \$y True if both \$x and \$y are true
|| Or \$x || \$y True if either \$x or \$y is true
! Not !\$x True if \$x is not true

Example :
<?php
\$x = 10;
\$y=20;

if(\$x==10 and \$y==20)
{
echo "True"."<br>";
}

if(\$x==10 or \$y==30)
{
echo "True"."<br>";
}

if(\$x==10 and \$y==20)
{
echo "False"."<br>";
}

if(\$x !==20)
{
echo "True"."<br>";
}
?>

Output :
True
True
False
True

String operators :

Operator Name Expression Description
. Concatenation \$txt_1 . \$txt_2 Concatenation of \$txt1 and \$txt2
.= Concatenation assignment \$txt_1 .= \$txt_2 Appends \$txt_2 to \$txt_1

Example :
<?php
\$txt_1 = "Hello";
\$txt_2 = " world";
echo \$txt_1 . \$txt_2."<br>";

\$txt_3 = "My";
\$txt_4= " PHP";
\$txt_3 .= \$txt_4;
echo \$txt_3;
?>

Output :
Hello world
My PHP

Array operators : Array operators are used in PHP to compare arrays.

Operator Name Expression Description
+ Union \$x + \$y Union of \$x and \$y
== Equality \$x == \$y Returns true if \$x and \$y have the same key/value pairs
=== Identity \$x === \$y Returns true if \$x and \$y have the same key/value pairs in the same order and of the same types
!= Inequality \$x != \$y Returns true if \$x is not equal to \$y
<> Inequality \$x <> \$y Returns true if \$x is not equal to \$y
!== Non-identity \$x !== \$y Returns true if \$x is not identical to \$y

Example :
<?php
\$x = array("a" => "red", "b" => "green");
\$y = array("c" => "blue", "d" => "yellow");
print_r(\$x + \$y);
?>

Output :
Array ( [a] => red [b] => green [c] => blue [d] => yellow )