using System;

using System.Collections.Generic;

using System.Linq;              

using System.Reflection;

using System.Diagnostics;

​

public class Person

{

    public string Name { get; set; }

    public int Age { get; set; }

}

​

public class Program

{

    public static void Main()

    {

​

        List<Person> personList = new List<Person>();

        personList.Add(new Person(){Name = "aaa", Age = 10});

        personList.Add(new Person(){Name = "bbb", Age = 5});

        for(int i = 0; i< 10; i++)

        {

            personList.AddRange(personList);

        }

​

        Dictionary<string, PropertyInfo> propDict = typeof(Person).GetProperties(BindingFlags.Public | BindingFlags.Instance)

            .Where(p => p.CanRead && !p.GetIndexParameters().Any()).AsEnumerable().ToDictionary(x => x.Name, x => x);

        int count = personList.Count;

        Stopwatch sw = new Stopwatch();

        //1. get Object[]

        sw.Restart();

        foreach(var prop in propDict)

        {

            var tempArray = personList.Select(x => prop.Value.GetValue(x)).ToArray();

            Console.WriteLine(tempArray.GetType().Name);//Object[]

        }

        sw.Stop();

        Console.WriteLine("Spend" + sw.ElapsedMilliseconds + "us");

        //2. not work, return Object[]

        sw.Restart();

        foreach(var prop in propDict)

        {

            var tempArray = personList.Select(x => Convert.ChangeType(prop.Value.GetValue(x), prop.Value.PropertyType)).ToArray();

            Console.WriteLine(tempArray.GetType().Name);//Object[]

        }

        sw.Stop();

        Console.WriteLine("Spend" + sw.ElapsedMilliseconds + "us");

        //3. work, via ArrayCopy, try to find other method

        sw.Restart();

        foreach(var prop in propDict)

        {

            var tempArray = personList.Select(x => prop.Value.GetValue(x)).ToArray();

            Array stronglyTypeArray = Array.CreateInstance(prop.Value.PropertyType, count);

            Array.Copy(tempArray, stronglyTypeArray, count);

            Console.WriteLine(stronglyTypeArray.GetType().Name);//String[]//Int32[]

        }

        sw.Stop();

        Console.WriteLine("Spend" + sw.ElapsedMilliseconds + "us");

        //4. work, if-condition slower than method 3

        sw.Restart();

        foreach(var prop in propDict)

        {

            dynamic tempArray;

            if(prop.Value.PropertyType == typeof(System.String))

            {

                tempArray = personList.Select(x =>  prop.Value.GetValue(x).ToString()).ToArray();

            }

            else if(prop.Value.PropertyType == typeof(System.Boolean))

            {

                tempArray = personList.Select(x =>  (bool)prop.Value.GetValue(x)).ToArray();

            }

            else if(prop.Value.PropertyType == typeof(System.Byte))

            {

                tempArray = personList.Select(x =>  (byte)prop.Value.GetValue(x)).ToArray();

            }

            else if(prop.Value.PropertyType == typeof(System.Char))

            {

                tempArray = personList.Select(x =>  (char)prop.Value.GetValue(x)).ToArray();

            }

            else if(prop.Value.PropertyType == typeof(System.Decimal))

            {

                tempArray = personList.Select(x =>  (decimal)prop.Value.GetValue(x)).ToArray();

            }

            else if(prop.Value.PropertyType == typeof(System.Double))

            {

                tempArray = personList.Select(x =>  (double)prop.Value.GetValue(x)).ToArray();

            }

            else if(prop.Value.PropertyType == typeof(System.Int16))

            {

                tempArray = personList.Select(x =>  (short)prop.Value.GetValue(x)).ToArray();

            }

            else if(prop.Value.PropertyType == typeof(System.Int32))

            {

                tempArray = personList.Select(x =>  (int)prop.Value.GetValue(x)).ToArray();

            }

            else if(prop.Value.PropertyType == typeof(System.Int64))

            {

                tempArray = personList.Select(x =>  (long)prop.Value.GetValue(x)).ToArray();

            }

            else if(prop.Value.PropertyType == typeof(System.Single))

            {

                tempArray = personList.Select(x =>  (float)prop.Value.GetValue(x)).ToArray();

            }

            else

            {

                tempArray = personList.Select(x =>  prop.Value.GetValue(x)).ToArray();

            }

            Console.WriteLine(tempArray.GetType().Name);//Object[]

        }

        sw.Stop();

        Console.WriteLine("Spend" + sw.ElapsedMilliseconds + "us");

    }

}