C# Win32 console application ignores Ctrl + C to prevent the program from exiting the code example (picture)

using System;
using System.Collections.Generic;
using System.Text;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Threading;

/************************************************************************/
/* CSharp_Win32控制台应用程序忽略 Ctrl + C
 * Powered by:testcs_dn
 * Blog:http://www.php.cn/
 */
/************************************************************************/
namespace CSharp_Win32控制台应用程序忽略CtrlC
{
    //定义处理程序委托
    public delegate bool ConsoleCtrlDelegate(int ctrlType);

    class Program
    {
        //导入SetCtrlHandlerHandler API
        [DllImport("kernel32.dll")]
        private static extern bool SetConsoleCtrlHandler(ConsoleCtrlDelegate HandlerRoutine, bool Add);
        //当用户关闭Console时，系统会发送次消息
        private const int CTRL_CLOSE_EVENT = 2;
        //Ctrl+C，系统会发送次消息
        private const int CTRL_C_EVENT = 0;
        //Ctrl+break，系统会发送次消息
        private const int CTRL_BREAK_EVENT = 1;
        //用户退出（注销），系统会发送次消息
        private const int CTRL_LOGOFF_EVENT = 5;
        //系统关闭，系统会发送次消息
        private const int CTRL_SHUTDOWN_EVENT = 6;

        static void Main(string[] args)
        {
            Program cls = new Program();
            //Console.ReadKey();
        }
        public Program()
        {
            ConsoleCtrlDelegate consoleDelegete = new ConsoleCtrlDelegate(HandlerRoutine);

            bool bRet = SetConsoleCtrlHandler(consoleDelegete, true);
            if (bRet == false) //安装事件处理失败
            {
                Console.WriteLine("error");
                while (true)
                {
                    Console.WriteLine("...");
                    Thread.Sleep(1000);
                }
            }
            else
            {
                Console.WriteLine("ok");
                while (true)
                {
                    Console.WriteLine("...");
                    Thread.Sleep(1000);
                }
            }

        }

        /// <summary>
        /// 处理程序例程，在这里编写对指定事件的处理程序代码
        /// 注意：在VS中调试执行时，在这里设置断点，但不会中断；会提示：无可用源；
        /// </summary>
        /// <param name="CtrlType"></param>
        /// <returns></returns>
        private static bool HandlerRoutine(int ctrlType)
        {
            switch(ctrlType)
            {
                case CTRL_C_EVENT:
                    Console.WriteLine("C");
                    return true; //这里返回true，表示阻止响应系统对该程序的操作
                    //break;
                case CTRL_BREAK_EVENT:
                    Console.WriteLine("BREAK");
                    break;
                case CTRL_CLOSE_EVENT:
                    Console.WriteLine("CLOSE");
                    break;
                case CTRL_LOGOFF_EVENT:
                    Console.WriteLine("LOGOFF");
                    break;
                case CTRL_SHUTDOWN_EVENT:
                    Console.WriteLine("SHUTDOWN");
                    break;
            }
            //return true;//表示阻止响应系统对该程序的操作
            return false;//忽略处理，让系统进行默认操作
        }
    }
}