PHP Arithmetic. Free online PHP and MySQL Web Database Programming Tutorial...

Arithmetic in PHP is very simple. PHP provides various arithmetic operators; for example:
addition +,
subtraction -,
multiplication *,
division /,
modulus %,
increment ++ and
decrement --.

PHP Addition
PHP provides + operator for addition. Consider the following piece of code:

$x = 2; // $x has a value 2
$x = $x + 2; // now $x has a value 4

PHP Subtraction
PHP provides - operator for subtraction. Consider the following piece of code:

$x = 2; // $x has a value 2
$x = $x - 1; // now $x has a value 1

PHP Multiplication
PHP provides * operator for multiplication. Consider the following piece of code:

$x = 2; // $x has a value 2
$x = $x * 3; // now $x has a value 6

PHP Division
PHP provides / operator for subtraction. Consider the following piece of code:

$x = 5; // $x has a value 5
$x = $x / 2; // now $x has a value 2.5

PHP Modulus Operation
PHP provides % operator for modulus operation. Modulus operation is also referred to as division remainder, as it returns the remainder after performing a division. Consider the following piece of code:

$x = 53; // $x has a value 53
$x = $x % 10; // now $x has a value 3

PHP Increment
PHP provides ++ operator for incrementing a number by 1. Consider the following piece of code:

$x = 5; // $x has a value 5
$y = ++$x; // $y has a value 6

PHP Decrement
PHP provides -- operator for decrementing a number by 1. Consider the following piece of code:

$x = 5; // $x has a value 5
$y = --$x; // $y has a value 4

Be careful when using the increments and the decrement operators in expressions. The position of the operators is very important in expressions, --$x means something very different from $x--. When we use

$y = --$x;

the value of x is decremented by 1 and then assigned to the the variable $y. On the other hand if we use

$y = $x--;

the old value of $x is assigned to the variable $y and after the assignment the value of $x is decremented by 1. Same rules apply to the PHP increment operator.

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