PHP Numbers

PHP has three primary numeric types:

• Integer
• Float
• Numeric strings

Additionally, PHP includes two more numeric data types:

• Infinity
• NaN (Not a Number)

Numeric type variables are created by assigning a value to them:

Example

To check the type of any variable in PHP, use the var_dump() function:

PHP Floats

A float is a number that includes a decimal point or is expressed in exponential form.

Examples of floats include 2.0, 256.4, 10.358, 7.64E+5, and 5.56E-5.

The float data type can typically store values up to 1.7976931348623E+308 (platform dependent) and has a maximum precision of 14 digits.

PHP provides the following predefined constants for floats (available since PHP 7.2):

• PHP_FLOAT_MAX: The largest representable floating-point number.
• PHP_FLOAT_MIN: The smallest representable positive floating-point number.
• PHP_FLOAT_DIG: The number of decimal digits that can be accurately rounded into a float and back without losing precision.
• PHP_FLOAT_EPSILON: The smallest representable positive number $x$ such that $x+1.0\ne 1.0$.

PHP also includes the following functions to check if a variable is of float type:

• is_float()
• is_double() (alias of is_float())

Example

Determine if a variable is of float type:

$x = 10.365;
var_dump(is_float($x));

PHP Infinity

A numeric value greater than PHP_FLOAT_MAX is regarded as infinite.

PHP provides the following functions to check if a numeric value is finite or infinite:

• is_finite()
• is_infinite()

Additionally, the var_dump() function in PHP returns both the data type and the value.

Example

Determine if a numeric value is finite or infinite:

$x = 1.9e411;
var_dump($x);

PHP NaN

NaN stands for “Not a Number.”

NaN is used to represent the result of undefined mathematical operations.

PHP provides the following function to check if a value is NaN:

• is_nan()

Additionally, the var_dump() function in PHP returns both the data type and the value.

Example

An invalid calculation will yield a NaN value.

$x = acos(8);
var_dump($x);

PHP Numerical Strings

The PHP is_numeric() function determines if a variable is numeric. It returns true if the variable is either a number or a numeric string; otherwise, it returns false.

Example

Verify if the variable is numeric:

$x = 5985;
var_dump(is_numeric($x));

$x = "5985";
var_dump(is_numeric($x));

$x = "59.85" + 100;
var_dump(is_numeric($x));

$x = "Hello";
var_dump(is_numeric($x));

PHP Casting Strings and Floats to Integers

Sometimes, it’s necessary to cast a numerical value to a different data type.

The (int), (integer), and intval() functions are commonly used to convert a value to an integer.

Example

Cast a float or string to an integer:

// Cast float to int
$x = 23465.768;
$int_cast = (int)$x;
echo $int_cast;

echo "<br>";

// Cast string to int
$x = "23465.768";
$int_cast = (int)$x;
echo $int_cast;