NCalc

NCalc is a fast, lightweight expression evaluator for .NET. It parses and evaluates mathematical and logical expressions with literals, operators, parameters, built-in functions, and custom functions.

NCalc targets modern .NET, .NET Standard 2.0, and .NET Framework 4.8.

Documentation

Start with the NCalc docs for the full language reference, runtime options, plugins, and API reference.

Useful entry points:

• Language reference
• Evaluation options
• Runtime features
• Extensibility and plugins

Install

Use NCalc for the expression engine:

dotnet add package NCalc

[!IMPORTANT] NCalc, NCalcSync, and NCalcAsync are redirect packages that currently point directly to NCalc.Core, preserving compatibility from before the community efforts were consolidated into the same repository.

Add optional packages only when you need them:

dotnet add package NCalc.LambdaCompilation
dotnet add package NCalc.DependencyInjection

Quick Examples

Evaluate an expression

using NCalc;

var result = new Expression("2 + 3 * 5").Evaluate();
// 17

Use parameters

var expression = new Expression("Round(Pow([x], 2) + [offset], 2)");
expression.Parameters["x"] = 3.14;
expression.Parameters["offset"] = 10;

var result = expression.Evaluate();
// 19.86

Add custom functions

var expression = new Expression("SecretOperation(3, 6)");
expression.Functions["SecretOperation"] = args =>
    (int)args.Evaluate(0) + (int)args.Evaluate(1);

var result = expression.Evaluate();
// 9

Compile to a lambda

Install NCalc.LambdaCompilation first.

using NCalc.LambdaCompilation;

var expression = new Expression("1 + 2");
Func<int> function = expression.ToLambda<int>();

var result = function();
// 3

For data types, operators, built-in functions, async evaluation, caching, expression serialization, and advanced configuration, check the docs.

Help

Open an issue for bugs or usage problems. Include the expression, the expected result, the actual result, and your NCalc version.

Learn More

• How to execute mathematical expressions in a string in .NET
• State of the Art Expression Evaluation

Related Projects

Using NCalc? Create a PR and add your project here!

Versioning

NCalc uses Nerdbank.GitVersioning. Each library build can be traced back to the original git commit. Read more in the release documentation.

Star History