Project Description

NCalc is a mathematical expressions evaluator in .NET. NCalc can parse any expression and evaluate the result, including static or dynamic parameters and custom functions.

For additional information on the technique we used to create this framework please read this article: http://www.codeproject.com/KB/recipes/sota_expression_evaluator.aspx.

For documentation here is the table of content:
  • description : overall concepts, usage and extensibility points
  • operators : available standard operators and structures
  • values : authorized values like types, functions, ...
  • functions : list of already implemented functions
  • parameters : on how to use parameters expressions

Functionnalities

Simple expressions

  Expression e = new Expression("2 + 3 * 5");
  Debug.Assert(17 == e.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()); // strings

Handles 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

  Expression e = new Expression("SecretOperation(3, 6)");
  e.EvaluateFunction += delegate(string name, FunctionArgs args)
      {
          if (name == "SecretOperation")
              args.Result = (int)args.Parameters[0].Evaluate() + (int)args.Parameters[1].Evaluate();
      };
  
  Debug.Assert(9 == e.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

  Expression e = new Expression("Round(Pow([Pi], 2) + Pow([Pi2], 2) + [X], 2)");

  e.Parameters["Pi2"] = new Expression("Pi * [Pi]");
  e.Parameters["X"] = 10;

  e.EvaluateParameter += delegate(string name, ParameterArgs args)
    {
      if (name == "Pi")
      args.Result = 3.14;
    };

  Debug.Assert(117.07 == e.Evaluate());

Last edited Jan 3, 2011 at 3:31 PM by sebastienros, version 8