AlgorithmEngine engine = new AlgorithmEngine();
    double a=0.0;
    if (engine.Parse("1+2")) {
        var o = engine.Evaluate();
        a=o.NumberValue;
    }
    var b = engine.TryEvaluate("1=1 && 1<2 and 7-8>1", 0);// 支持 && || and or 
    var c = engine.TryEvaluate("2+3", 0);
    var d = engine.TryEvaluate("count({1,2,3,4})", 0);//{}代表数组,返回:4
    var s = engine.TryEvaluate("'aa'&'bb'", ""); //字符串连接,返回:aabb
    var r = engine.TryEvaluate("(1=1)*9+2", 0); //返回:11
    var d = engine.TryEvaluate("'2016-1-1'+1", DateTime.MinValue); //返回日期:2016-1-2
    var t = engine.TryEvaluate("'2016-1-1'+9*'1:0'", DateTime.MinValue);//返回日期:2016-1-1 9:0
    var j = engine.TryEvaluate("json('{\"Name\":\"William Shakespeare\",\"Age\":51,\"Birthday\":\"04/26/1564 00:00:00\"}').Age", null);//返回51
    var k = engine.TryEvaluate("json('{\"Name\":\"William Shakespeare   \",\"Age\":51,\"Birthday\":\"04/26/1564 00:00:00\"}')[Name].Trim()", null);//返回"William Shakespeare" (不带空格)
    var l = engine.TryEvaluate("json('{\"Name1\":\"William Shakespeare \",\"Age\":51,\"Birthday\":\"04/26/1564 00:00:00\"}')['Name'& 1].Trim().substring(2,3)", null); ;//返回"ill"

    //定义圆柱信息
    public class Cylinder : AlgorithmEngine
    {
        private int _radius;
        private int _height;
        public Cylinder(int radius, int height)
        {
            _radius = radius;
            _height = height;
        }

        protected override Operand GetParameter(string parameter)
        {
            if (parameter == "半径")
            {
                return Operand.Create(_radius);
            }
            if (parameter == "直径")
            {
                return Operand.Create(_radius * 2);
            }
            if (parameter == "高")
            {
                return Operand.Create(_height);
            }
            return base.GetParameter(parameter);
        }
    }
    //调用方法
    Cylinder c = new Cylinder(3, 10);
    c.TryEvaluate("[半径]*[半径]*pi()", 0.0);      //圆底面积
    c.TryEvaluate("[直径]*pi()", 0.0);            //圆的长
    c.TryEvaluate("[半径]*[半径]*pi()*[高]", 0.0); //圆的体积
    c.TryEvaluate("['半径']*[半径]*pi()*[高]", 0.0); //圆的体积