保证程序只有一个实例运行并且先将旧实例关闭再运行新实例

using  System;
using  System.Collections.Generic;
using  System.Windows.Forms;
using  System.Threading;
using  System.Diagnostics;
using  System.Reflection;

namespace  MyClient
{
    
     static   class  Program
    {
         ///  

         ///  The main entry point for the application.
         ///  

        [STAThread]
         static   void  Main( string [] args)
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault( false );
             // bool blnCreate;//Another method to make sure only one instance
             // Mutex m = new Mutex(true, "MyClient", out blnCreate);
             // if (blnCreate)
            CloseRunningInstance();
            Application.Run( new  MainFrm());
        }
         // Close the existed instance of my application
         static   void  CloseRunningInstance()
        {
            Process current  =  Process.GetCurrentProcess();
            Process[] processes  =  Process.GetProcessesByName(current.ProcessName);
             // Loop through the running processes in with the same name    
             foreach  (Process process  in  processes)
            {
                 // Ignore the current process    
                 if  (process.Id  !=  current.Id)
                {
                     // Make sure that the process is running from the exe file.    
                     if  (Assembly.GetExecutingAssembly().Location.Replace( " / " ,  " \\ " )  ==  current.MainModule.FileName)
                    {
                         // Close the other process instance.   
                        process.Kill();
                        process.WaitForExit();
                    }
                }
            }
        } 
    }
}