C#正则表达式提取数字或大小写字母

using System;
using System.Text.RegularExpressions;

namespace RegExApplication
{
    class Program
    {

        static void Main(string[] args)
        {
            //1、纯数字提取
            Console.WriteLine("纯数字提取:" + Regex.Replace("abAB 001 2dd", @"[^0-9]+", ""));

            //2、带有小数点数字提取
            Console.WriteLine("带有小数点数字提取：" + Regex.Replace("abA2d1.255d", @"[^d.d]", ""));

            //3、大写字母提取
            Console.WriteLine("大写字母提取:" + Regex.Replace("abAB 001 2dd", @"[^A-Z]+", ""));

            //4、小写字母提取
            Console.WriteLine("小写字母提取:" + Regex.Replace("abAB 001 2dd", @"[^a-z]+", ""));

            //5、数字或大小写字母提取
            Console.WriteLine("数字或大小写字母提取:" + Regex.Replace("abAB $%001 &2%dd", @"[^A-Za-z0-9]+", ""));

            
            Console.ReadKey();
        }
    }
}