Lambda创建表达式目录树

using System;
using System.Linq.Expressions;

namespace Demo
{
    class Program
    {
        static void Main(string[] args)
        {
            Func<int, int, int> func = null;
            //两个参数
            ParameterExpression a = Expression.Parameter(typeof(int), "a");
            ParameterExpression b = Expression.Parameter(typeof(int), "b");

            //求积
            BinaryExpression cj = Expression.Multiply(a, b);

            //常量
            ConstantExpression Con2 = Expression.Constant(4);

            //求和
            BinaryExpression Add = Expression.Add(cj, Con2);

            //创建一个表示lambda表达式的对象
            Expression<Func<int, int, int>> lexp = Expression.Lambda<Func<int, int, int>>(cj, a, b);
            func = lexp.Compile();  //表达目录树生成委托
            //查看表达式
            Console.WriteLine(lexp.ToString());  //
            var ss = func.Invoke(1, 2);  //执行委托返回结果
            Console.WriteLine(ss);


            //创建一个表示lambda表达式的对象
            Expression<Func<int, int, int>> lexp1 = Expression.Lambda<Func<int, int, int>>(Add, a, b);
            func = lexp1.Compile();   //表达目录树生成委托
            //查看表达式
            Console.WriteLine(lexp1.ToString());
            var ss1 = func.Invoke(1, 2);   //执行委托返回结果
            Console.WriteLine(ss1);

            Console.ReadKey();
        }
    }
}