NCalc is a fast and lightweight expression evaluator library for .NET, designed for flexibility and high performance. It supports a wide range of mathematical and logical operations. NCalc can parse any expression and evaluate the result, including static or dynamic parameters and custom functions. NCalc targets .NET 8, .NET Standard 2.0 and NET Framework 4.8.
Need help or want to learn more? Check our docs.
For additional information on the technique we used to create this framework please read this article.
Important
If you need help, please open an issue and include the expression to help us better understand the problem. Providing this information will aid in resolving the issue effectively.
If you want to evaluate simple expressions:
dotnet add package NCalcSync
Want async support at your functions and parameters?
dotnet add package NCalcAsync
Dependency Injection? We got you covered:
dotnet add package NCalc.DependencyInjection
var expression = new Expression("2 + 3 * 5");
Debug.Assert(17 == expression.Evaluate());Evaluates .NET data types
Debug.Assert(123456 == new Expression("123456").Evaluate()); // integers
Debug.Assert(new DateTime(2001, 01, 01) == new Expression("#01/01/2001#").Evaluate()); // date and times
Debug.Assert(123.456 == new Expression("123.456").Evaluate()); // floating point numbers
Debug.Assert(true == new Expression("true").Evaluate()); // booleans
Debug.Assert("azerty" == new Expression("'azerty'").Evaluate()); // stringsHandles mathematical functional from System.Math
Debug.Assert(0 == new Expression("Sin(0)").Evaluate());
Debug.Assert(2 == new Expression("Sqrt(4)").Evaluate());
Debug.Assert(0 == new Expression("Tan(0)").Evaluate());Evaluates custom functions
var expression = new Expression("SecretOperation(3, 6)");
expression.Functions["SecretOperation"] = (args) => {
return (int)args[0].Evaluate() + (int)args[1].Evaluate();
};
Debug.Assert(9 == expression.Evaluate());Handles unicode characters
Debug.Assert("経済協力開発機構" == new Expression("'経済協力開発機構'").Evaluate());
Debug.Assert("Hello" == new Expression(@"'\u0048\u0065\u006C\u006C\u006F'").Evaluate());
Debug.Assert("だ" == new Expression(@"'\u3060'").Evaluate());
Debug.Assert("\u0100" == new Expression(@"'\u0100'").Evaluate());Define parameters, even dynamic or expressions
var expression = new Expression("Round(Pow([Pi], 2) + Pow([Pi2], 2) + [X], 2)");
expression.Parameters["Pi2"] = new Expression("Pi * [Pi]");
expression.Parameters["X"] = 10;
expression.DynamicParameters["Pi"] = _ => {
Console.WriteLine("I'm evaluating π!");
return 3.14;
};
Debug.Assert(117.07 == expression.Evaluate());JSON Serialization
At .NET 8+, NCalc have built-in support to polymorphic JSON serialization using System.Text.Json.
const string expressionString = "{waterLevel} > 4.0";
var logicalExpression = LogicalExpressionFactory.Create(expressionString, ExpressionOptions.NoCache); //Created a BinaryExpression object.
var jsonExpression = JsonSerializer.Serialize(parsedExpression);
var deserializedLogicalExpression = JsonSerializer.Deserialize<LogicalExpression>(jsonExpression); //The object is still a BinaryExpression.
var expression = new Expression(deserializedLogicalExpression);
expression.Parameters = new Dictionary<string, object> {
{"waterLevel", 4.0}
};
var result = expression.Evaluate();Caching
NCalc automatically cache the parsing of strings using a ConcurrentDictionary.
You can also use our Memory Cache plugin.
Lambda Expressions
var expression = new Expression("1 + 2");
Func<int> function = expression.ToLambda<int>();
Debug.Assert(function()); //3Fast and lightweight parser creation tools by Sébastien Ros that NCalc uses at its parser.
Extension functions for NCalc to handle many general functions,
including string functions, switch, if, in, typeOf, cast etc.
Developed by David, Dan and all at Panoramic Data.
JavaScript Interpreter for .NET by Sébastien Ros, the author of NCalc library.
Runs on any modern .NET platform as it supports .NET Standard 2.0 and .NET 4.6.1 targets (and up).
A TypeScript/JavaScript port of NCalc.
NCalc 101 is a simple web application that allows you to try out the NCalc expression evaluator, developed by Panoramic Data.
JJMasterData is a runtime form generator from database metadata. It uses NCalc to evaluate expressions used in field visibility and other dynamic behaviors.
The project uses Nerdbank.GitVersioning tool to manage versions.
Each library build can be traced back to the original git commit.
Read more about versioning here.
If you want to talk with us, get support or just get the latest NCalc news, come to our discord server.
