The Decimal class is under the Decimal namespace.

Decimal objects can be constructed using a Decimal, string, or int value, and an optional precision which defaults to 28.

Special float values are also supported (NAN, INF and -INF), but float is otherwise not a valid argument in order to avoid accidentially using a float. If you absolutely must use a float to construct a decimal you can cast it to a string first, but doing so if affected by the precision INI setting.

Projects using this extension should avoid float entirely, wherever possible. An example workflow is to store values as DECIMAL in the database, query them as string, parse to Decimal, perform calculations, and finally prepare for the database using toFixed.

JSON conversions will automatically convert the decimal to string using all signficant figures.

A warning will be raised if value was not parsed completely. For example, "0.135" to a precision of 2 will result in "0.14" with a warning. Similarly, 123 with a precision of 2 would result in 120 with a warning because data has been lost.

Decimal is final and immutable. Arithmetic operations always return a new Decimal using the maximum precision of the object and the operands. The result is therefore accurate up to MAX($this->precision(), $op1->precision(), ...) significant figures, subject to rounding of the last digit.

For example:

use Decimal\Decimal;

$a = new Decimal("1", 2);
$b = new Decimal("7", 8);

print_r($a / $b);

Decimal\Decimal Object
(
    [value] => 0.14285714
    [precision] => 8
)

Scalar operands inherit the precision of the Decimal operand, which avoids the need to construct a new object for the operation. If a scalar operand must be parsed with a higher precision, you should construct a new Decimal with an explicit precision. The result of a decimal operation is always a Decimal.

For example:

use Decimal\Decimal;

$op1 = new Decimal("0.1", 4);
$op2 = "0.123456789";

print_r($op1 + $op2);


use Decimal\Decimal;

/**
 * @param int $n The factorial to calculate, ie. $n!
 * @param int $p The precision to calculate the factorial to.
 *
 * @return Decimal
 */
function factorial(int $n, int $p = Decimal::DEFAULT_PRECISION): Decimal
{
    return $n < 2 ? new Decimal($n, $p) : $n * factorial($n - 1, $p);
}

echo factorial(10000, 32);

Warning: Loss of data on string conversion in ... on line 1
Decimal\Decimal Object
(
    [value] => 0.2235
    [precision] => 4
)