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PHP Arithmetic Operators

Summary: in this tutorial, you will learn about the arithmetic operators including addition, subtraction, multiplication, division, exponentiation, and modulo to perform arithmetic operations.

Introduction to PHP arithmetic operators #

PHP provides common arithmetic operators that allow you to perform addition, subtraction, multiplication, division, exponentiation, and modulus operations.

The arithmetic operators require numeric values. If you apply an arithmetic operator to non-numeric values, PHP will attempt to convert them to numeric values before performing arithmetic operations.

The following table displays the arithmetic operators in PHP:

OperatorNameExampleDescription
+Addition$x * $yReturn the sum of $x and $y
–Subtraction$x – $yReturn the difference of $x and $y
*Multiplication$x * $yReturn the product of $x and $y
/Division$x / $yReturn the quotient of $x and $y
%Modulo$x % $yReturn the remainder of $x divided by $y
**Exponentiation$x ** $yReturn the result of raising $x to the power of  $y.

Addition operator #

The addition operator (+) adds two numbers and returns their sum. You can use the addition operator with integers and floats.

The sum of two integers will result in an integer:

<?php

$x = 10;
$y = 20;

$z = $x + $y;

var_dump($z);

Try it

Output:

int(30)

The sum of an integer with a float or two floats will result in a float:

<?php

$x = 10;
$y = 2.0;

$z = $x + $y;

var_dump($z);

Try it

Output:

float(12)

Computers cannot represent floats precisely. In some cases, the result will not be what you expect. For example:

<?php

$z = 0.1 + 0.1 + 0.1;

var_dump($z);

Try it

Output:

float(0.30000000000000004)

You’ll encounter an issue If you add floats and compare the result with another float. For example, the following returns false instead of true:

<?php

$z = 0.1 + 0.1 + 0.1;

var_dump($z === 0.3);

Try it

Output:

bool(false)

If you add a number and a string, PHP will attempt to convert the string to a number before performing the calculation:

<?php

$x = 1 + '2';
echo $x;

Try it

Output:

<?php

$x = 1 + '2';
echo $x;

Try it

If the string contains a non-numeric value, PHP will issue a warning. For example:

<?php

$x = 1 + '2a';
echo $x;

Try it

Warning:

Warning: A non-numeric value encountered

If PHP cannot convert the string to a number, it’ll issue fatal and type errors:

<?php

$x = 1 + 'a';
echo $x;

Try it

Error:

Fatal error: Uncaught TypeError: Unsupported operand types: int + string
TypeError: Unsupported operand types: int + string

Subtraction operator #

The subtraction operator subtracts the second from the first:

<?php

$x = 20;
$y = 10;

$z = $x - $y;
var_dump($z);

Try it

Output:

int(10)

If you subtract a float from another float or integer, the result will be a float:

<?php

$x = 3.0;
$y = 1.0;

$z = $x - $y;
var_dump($z);

Try it

Output:

float(2)

Like the addition operator, subtracting a float from another will sometimes result in inaccurate numbers. For example:

<?php

$x = 0.3 - 0.1;
var_dump($x);

Try it

Output:

float(0.19999999999999998)

Multiplication Operator #

The multiplication operator multiplies two numbers. For example:

<?php

$x = 10;
$y = 20;

$z = $x * $y;

var_dump($z);

Try it

Output:

int(200)

When you multiply a float with an integer or float, the result will be a float:

<?php

$x = 10;
$y = 1.0;

$z = $x * $y;
var_dump($z);

Try it

Output:

float(10)

Division operator #

The division operator divides the first number by the second one. For example:

<?php

$x = 20;
$y = 10;

$z = $x / $y;

var_dump($z);

Try it

Output:

int(2)

If you attempt to divide a number by zero, you’ll get a fatal error:

<?php

$x = 10 / 0;

Try it

Error:

Fatal error: Uncaught DivisionByZeroError: Division by zero

Modulus operator #

The modulus operator (%) returns the remainder of the division:

<?php

$x = 5;
$y = 2;

$z = $x / $y;
var_dump($z);

Try it

Output:

float(2.5)

Exponentiation operator #

The exponentiation operator (**) raises a number to the power of another number. For example:

<?php

$result  = 10 ** 3;

var_dump($result);

Try it

Output:

int(1000)

Summary #

  • Use the addition operator (+) to add two numbers.
  • Use the subtraction operator (-) to subtract a second number from the first number.
  • Use the multiplication operator (*) to multiply two numbers.
  • Use the division operator (/) to divide the first number by the second.
  • Use the modulus operator (%) to return the remainder of the division.
  • Use the exponentiation operator (**) to raise a number to a power of another number.

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