arithmexp

arithmexp is a powerful mathematical expression parser and evaluator library for PHP with support for variable substitution, constant declaration, deterministic and non-deterministic function registration, and more. Test out the parser on the demo site!

Installation with composer

composer require muqsit/arithmexp

Evaluating a mathematical expression

To evaluate a mathematical expression, a Parser instance must first be constructed. The mathematical expression string must be passed in Parser::parse() to obtain a reusable Expression instance. The value of the mathematical expression can then be evaluated by invoking Expression::evaluate().

$parser = Parser::createDefault();
$expression = $parser->parse("2 + 3");
var_dump($expression->evaluate()); // int(5)

To substitute values of variables that occur within the supplied expression, an array<string, int|float> must be passed to Expression::evaluate().

$expression = $parser->parse("x + y");
var_dump($expression->evaluate(["x" => 2, "y" => 3])); // int(5)
var_dump($expression->evaluate(["x" => 1.5, "y" => 1.5])); // float(3)

The return value type of the evaluation is consistent with that of PHP's. As such, int + int returns an int value, whereas a float + int|float returns a float value. See documentation notes in the wiki for more details.