Money (PHP 8.1)

A small, precise money helper class for arithmetic operations and comparisons with configurable decimal precision. Uses bcmath for deterministic decimal calculations.

• Namespace: Ecommerce
• PHP: 8.1+
• Requires: PHP extension ext-bcmath

Installation

composer require ecommerce-utilities/money

• Ensure the bcmath PHP extension is enabled (e.g., sudo apt-get install php-bcmath and restart your web server/CLI).
• Include the class in your project (e.g., via PSR-4 autoloading) and use the Ecommerce namespace.

Quickstart

<?php

use Ecommerce\Money;

// Create
$price  = Money::fromValue(19.99);         // Default: 2 decimal places
$tax    = Money::fromValue(1.90, 2);       // explicit precision
$zero   = Money::zero();                   // 0.00

// Arithmetic
$total  = Money::add($price, $tax);        // 21.89
$rest   = Money::sub($total, 5);           // 16.89
$multi  = Money::mul($rest, 3);            // 50.67
$share  = Money::div($multi, 4);           // 12.67 (with 2 decimals)

// Comparisons
$isSame      = Money::isEqual(10, '10.00');                 // true
$isLeftGt    = Money::isLeftSideGreater(5, 7);              // true (5 < 7)
$isRightGt   = Money::isRightSideGreater(9.99, 9.98);       // true (9.99 > 9.98)

// Access and string representation
$asFloat = $total->getValue();             // float 21.89
$dp      = $total->getDecimalPrecision();  // int 2
echo (string) $total;                      // "21.89"

Controlling precision

• The default precision is 2 decimal places.
• You can set precision explicitly in several places:
  • When creating: Money::fromValue(123.456, 3)
  • In operations: Money::add($a, $b, 3)
• During operations, precision is determined as follows:
  1. The provided $decimalPrecision parameter (if set),
  2. otherwise, the precision of a Money operand (if present),
  3. otherwise, 2.

Examples:

<?php

use Ecommerce\Money;

$a = Money::fromValue(1.2345, 4);
$b = 2;

$sumDefault = Money::add($a, $b);          // uses 4 from the Money operand -> "3.2345"
$sumForced  = Money::add($a, $b, 3);       // overrides -> "3.235"

Null, string, and float inputs

All methods accept Money, int, float, numeric-string, or null (depending on the method):

<?php

use Ecommerce\Money;

Money::add(null, 10);        // 10.00
Money::add(null, null);      // 0.00 (Money::zero())
Money::sub(null, 5);         // 0.00
Money::mul(10, null);        // 0.00
Money::div(10, 0);           // 10.00 (division by 0 returns the left operand)

Notes:

• fromMoney($value) returns the numeric value (float) regardless of the input type.
• The string representation is always formatted according to the set precision, e.g., "12.30".

Best practices

• Define a consistent precision for a domain (e.g., currency: 2, crypto assets: 8).
• For critical calculations, pass the precision explicitly to add/sub/mul/div.
• Use the comparison helpers instead of direct float comparisons.

API overview

• Creation:
  • Money::fromValue(null|Money|int|float|string $value, ?int $decimalPrecision = null): Money
  • Money::zero(): Money
• Arithmetic:
  • Money::add($a, $b, ?int $decimalPrecision = null): Money
  • Money::sub($a, $b, ?int $decimalPrecision = null): Money
  • Money::mul($a, $b, ?int $decimalPrecision = null): Money
  • Money::div($a, $b, ?int $decimalPrecision = null): Money
• Comparisons:
  • Money::isEqual($a, $b, ?int $decimalPrecision = null): bool
  • Money::isLeftSideGreater($a, $b, ?int $decimalPrecision = null): bool // true when a < b
  • Money::isRightSideGreater($a, $b, ?int $decimalPrecision = null): bool // true when a > b
• Access:
  • $money->getValue(): float
  • $money->getDecimalPrecision(): int
  • (string) $money for formatted output

License

Feel free to use this class in your projects. Contributions and improvements are welcome.