PHP Operators - Arithmetic, Logical, Assignment Operators

Operators are symbols that instruct the PHP processor to carry out specific actions. For example, the addition (+) symbol instructs PHP to add two variables or values, whereas the greater-than (>) symbol instructs PHP to compare two values.

PHP operators are grouped as follows:

Arithmetic operators
Assignment operators
Comparison operators
Increment/Decrement operators
Logical operators
String operators
Array operators
Conditional assignment operators

Arithmetic Operators

The PHP arithmetic operators are used in conjunction with numeric values to perform common arithmetic operations such as addition, subtraction, multiplication, and so on.

Operator	Name	Example	Output
`+`	Addition	$x + $y	Sum of $x and $y
`-`	Subtraction	$x - $y	Difference of $x and $y
`*`	Multiplication	$x * $y	Product of $x and $y
`/`	Division	$x / $y	Quotient of $x and $y
`%`	Modulus	$x % $y	Remainder of $x divided by $y
`**`	Exponentiation	$x ** $y	Result of raising $x to the $y'th power

Sample usage of Arithmetic Operators:


        <?php
        

        $x = 10;
        $y = 4;
        echo($x + $y) . "<br>"; // 0utputs: 14
        echo($x - $y) . "<br>"; // 0utputs: 6
        echo($x * $y) . "<br>"; // 0utputs: 40
        echo($x / $y) . "<br>"; // 0utputs: 2.5
        echo($x % $y) . "<br>"; // 0utputs: 2

Assignment Operators

Assignment operators are used to assign values to variables.

Operator	Name	Example	Output
`=`	Assign	$x = $y	The left operand gets set to the value of the expression on the right
`+=`	Add and assign	$x += $y	Addition
`-=`	Subtract and assign	$x -= $y	Subtraction
`*=`	Multiply and assign	$x *= $y	Multiplication
`/=`	Divide and assign quotient	$x /= $y	Division
`%=`	Divide and assign modulus	Modulus

Sample usage of Assignment Operators:


        <?php
        

        $x = 10;
        echo $x . "<br>"; // Outputs: 10
        
 
        $x = 20;
        $x += 30;
        echo $x . "<br>"; // Outputs: 50
        
 
        $x = 50;
        $x -= 20;
        echo $x . "<br>"; // Outputs: 30
        
 
        $x = 5;
        $x *= 25;
        echo $x . "<br>"; // Outputs: 125
        
 
        $x = 50;
        $x /= 10;
        echo $x . "<br>"; // Outputs: 5
        
 
        $x = 100;
        $x %= 15;
        echo $x . "<br>"; // Outputs: 10

Comparison Operators

Comparison operators are used to compare two values in a Boolean fashion.

Operator	Name	Example	Output
`==`	Equal	$x == $y	True if $x is equal to $y
`===`	Identical	$x === $y	True if $x is equal to $y, and they are of the same type
`!=`	Not equal	$x != $y	True if $x is not equal to $y
`<>`	Not equal	$x <> $y	True if $x is not equal to $y
`!==`	Not identical	$x !== $y	True if $x is not equal to $y, or they are not of the same type
`<`	Less than	$x < $y	True if $x is less than $y
`>`	Greater than	$x > $y	True if $x is greater than $y
`>=`	Greater than or equal to	$x >= $y	True if $x is greater than or equal to $y
`<=`	Less than or equal to	$x <= $y	True if $x is less than or equal to $y

Sample usage of Comparison Operators:


        <?php
        

        $x = 25;
        $y = 35;
        $z = "25";
        var_dump($x == $z);  // Outputs: boolean true
        echo "<br>";
        var_dump($x === $z); // Outputs: boolean false
        echo "<br>";
        var_dump($x != $y);  // Outputs: boolean true
        echo "<br>";
        var_dump($x !== $z); // Outputs: boolean true
        echo "<br>";
        var_dump($x < $y);   // Outputs: boolean true
        echo "<br>";
        var_dump($x > $y);   // Outputs: boolean false
        echo "<br>";
        var_dump($x <= $y);  // Outputs: boolean true
        echo "<br>";
        var_dump($x >= $y);  // Outputs: boolean false
        echo "<br>";

Increment / Decrement Operators

Increment operators are used to increment a variable's value while decrement operators are used to decrement.

Operator	Name	Output
`++$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

Sample usage of Increment / Decrement Operators:


        <?php
        

        $x = 10;
        echo ++$x . "<br>"; // Outputs: 11
        echo $x . "<br>";   // Outputs: 11
        

        $x = 10;
        echo $x++ . "<br>"; // Outputs: 10
        echo $x . "<br>";   // Outputs: 11
        

        $x = 10;
        echo --$x . "<br>"; // Outputs: 9
        echo $x . "<br>";   // Outputs: 9
        

        $x = 10;
        echo $x-- . "<br>"; // Outputs: 10
        echo $x . "<br>";   // Outputs: 9

Logical Operators

Logical operators are typically used to combine conditional statements.

Operator	Name	Example	Output
`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 $y are `true`
`		`	Or
`!`	Not	!$x	`true` if $x is not `true`

Sample usage of Logical Operators:


        <?php
        

        $year = 2021;
        // Leap years are divisible by 400 or by 4 but not 100
        if(($year % 400 == 0) || (($year % 100 != 0) && ($year % 4 == 0))){
            echo "$year is a leap year.";
        } else{
            echo "$year is not a leap year.";
        }

String Operators

String operators are specifically designed for strings.

Operator	Name	Example	Output
`.`	Concatenation	$str1 . $str2	Concatenation of $str1 and $str2
`.=`	Concatenation assignment	$str1 .= $str2	Appends the $str2 to the $str1

Sample usage of String Operators:


        <?php
        

        $x = "Hello";
        $y = " World!";
        echo $x . $y . "<br>"; // Outputs: Hello World!
        
 
        $x .= $y;
        echo $x . "<br>"; // Outputs: Hello World!

Array Operators

Array operators are used to compare arrays.

Operator	Name	Example	Output
`+`	Union	$x + $y	Union of $x and $y
`==`	Equality	$x == $y	True if $x and $y have the same key/value pairs
`===`	Identity	$x === $y	True if $x and $y have the same key/value pairs in the same order and of the same types
`!=`	Inequality	$x != $y	True if $x is not equal to $y
`<>`	Inequality	$x <> $y	True if $x is not equal to $y
`!==`	Non-identity	$x !== $y	True if $x is not identical to $y

Sample usage of String Operators:


        <?php
        

        $x = array("a" => "Red", "b" => "Green", "c" => "Blue");
        $y = array("u" => "Yellow", "v" => "Orange", "w" => "Pink");
        $z = $x + $y; // Union of $x and $y
        var_dump($z);
        echo "<br>";
        var_dump($x == $y);   // Outputs: boolean false
        echo "<br>";
        var_dump($x === $y);  // Outputs: boolean false
        echo "<br>";
        var_dump($x != $y);   // Outputs: boolean true
        echo "<br>";
        var_dump($x <> $y);   // Outputs: boolean true
        echo "<br>";
        var_dump($x !== $y);  // Outputs: boolean true
        echo "<br>";

Conditional Assignment Operators

Conditional assignment operators are used to set a value depending on conditions.

Operator	Name	Example	Output
`?:`	Ternary	$x = expr1 ? expr2 : expr3	Returns the value of $x. The value of $x is expr2 if expr1 = `true`. The value of $x is expr3 if expr1 = `false`
`??`	Null coalescing	$x = expr1 ?? expr2	Returns the value of $x. The value of $x is expr1 if expr1 exists, and is not `null`. If expr1 does not exist, or is `null`, the value of $x is expr2. Introduced in PHP 7

Sample usage of Conditional Assignment Operators:


        <?php
        

        // if empty($user) = true, set $status = "anonymous"
        echo $status = (empty($user)) ? "anonymous" : "logged in";
        echo("<br>");
        

        $user = "John Doe";
        // if empty($user) = false, set $status = "logged in"
        echo $status = (empty($user)) ? "anonymous" : "logged in";
        echo "<br>";
        

        // variable $user is the value of $_GET['user']
        // and 'anonymous' if it does not exist
        echo $user = $_GET["user"] ?? "anonymous";
        echo("<br>");
        

        // variable $color is "red" if $color does not exist or is null
        echo $color = $color ?? "red";
        echo "<br>";

Exercise

Create the following variables: $num1, $num2, $num3. Assign the integer 3 to $num1 and 9 to $num2. Multiply $num1 by $num2 and assign the product to $num3. Print the result on $num3


        <?php
        

        $var = 123;


        <?php
        

        $num1 = 3;
        $num2 = 9;
        $num3 = $num1 * $num2;
        echo $num3;


        {
            "test_output_contains":{
                "expected":"27",
                "error_message":"Did you assign the correct value for your variables?"
            },
            "test_variable_exists":[
            {
                "object":"$num1",
                "error_message":"Have you declared <code>$num1<\/code>?"
            },
            {
                "object":"$num2",
                "error_message":"Have you declared <code>$num2<\/code>?"
            },
            {
                "object":"$num3",
                "error_message":"Have you declared <code>$num3<\/code>?"
            }
            ],
            "success_message":"Good job!",
            "error_message":"Please read the instructions again."
        }

Operators - PHP Basics

Arithmetic Operators

Assignment Operators

Comparison Operators

Increment / Decrement Operators

Logical Operators

String Operators

Array Operators

Conditional Assignment Operators

Exercise

Introduction

PHP Basics

PHP Advance

PHP OOP

PHP Functions and Methods