class Program
  {
    [STAThread]
    static void Main(string[] args)
    {
      //防止程序多次运行
      if (!OneInstance.IsFirst("MyTest"))
      {
        Console.WriteLine("警告:程序正在运行中! 请不要重复打开程序!可在右下角系统栏找到!");
        return;
      }
      Console.WriteLine("正在运行中");
      Console.ReadLine();
    }
  }
  public static class OneInstance
  {
    ///<summary>
    ///判断程序是否正在运行 
    ///</summary>
    ///<param name="appId">程序名称</param>
    ///<returns>如果程序是第一次运行返回True,否则返回False</returns>
    public static bool IsFirst(string appId)
    {
      bool ret = false;
      if (OpenMutex(0x1F0001, 0, appId) == IntPtr.Zero)
      {
        CreateMutex(IntPtr.Zero, 0, appId);
        ret = true;
      }
      return ret;
    }
    [DllImport("Kernel32.dll", CharSet = CharSet.Auto)]
    private static extern IntPtr OpenMutex(
      uint dwDesiredAccess, // access 
      int bInheritHandle,  // inheritance option 
      string lpName     // object name 
      );
    [DllImport("Kernel32.dll", CharSet = CharSet.Auto)]
    private static extern IntPtr CreateMutex(
      IntPtr lpMutexAttributes, // SD 
      int bInitialOwner,            // initial owner 
      string lpName              // object name 
      );
  }

string MnName = Process.GetCurrentProcess().MainModule.ModuleName;
 //返回不具有扩展名的制定路径字符串的文件名
String Pname = Path.GetFileNameWithoutExtension(MnName);
Process[] myprocess = Process.GetProcessesByName(Pname);
if (myprocess.Length > 1)
{
  MessageBox.Show("yici", "tishi", MessageBoxButtons.OK, MessageBoxIcon.Information);
}
else
{
  //Application.EnableVisualStyles();
  ////Application.SetCompatibleTextRenderingDefault(false);
  //Application.Run(new Form1());
}

static class Program
  {
    /// <summary>
    /// The main entry point for the application.
    /// </summary>
    [STAThread]
    static void Main()
    {
      bool createdNew;
      //系统能够识别有名称的互斥，因此可以使用它禁止应用程序启动两次
      //第二个参数可以设置为产品的名称:Application.ProductName

      //每次启动应用程序，都会验证名称为SingletonWinAppMutex的互斥是否存在
      Mutex mutex = new Mutex(false, "SingletonWinAppMutex", out createdNew);
      
      //如果已运行，则在前端显示
      //createdNew == false，说明程序已运行
      if (!createdNew)
      {
        Process instance = GetExistProcess();
        if (instance != null)
        {
          SetForegroud(instance);
          Application.Exit();
          return;
        }
      }
      Application.EnableVisualStyles();
      Application.SetCompatibleTextRenderingDefault(false);
      Application.Run(new MainForm());
    }

    /// <summary>
    /// 查看程序是否已经运行
    /// </summary>
    /// <returns></returns>
    private static Process GetExistProcess()
    {
      Process currentProcess = Process.GetCurrentProcess();
      foreach (Process process in Process.GetProcessesByName(currentProcess.ProcessName))
      {
        if ((process.Id != currentProcess.Id) && 
          (Assembly.GetExecutingAssembly().Location == currentProcess.MainModule.FileName))
        {
          return process;
        }
      }
      return null;
    }

    /// <summary>
    /// 使程序前端显示
    /// </summary>
    /// <param name="instance"></param>
    private static void SetForegroud(Process instance)
    {
      IntPtr mainFormHandle = instance.MainWindowHandle;
      if (mainFormHandle != IntPtr.Zero)
      {
        ShowWindowAsync(mainFormHandle, 1);
        SetForegroundWindow(mainFormHandle);
      }
    }

    [DllImport("User32.dll")]
    private static extern bool SetForegroundWindow(IntPtr hWnd);

    [DllImport("User32.dll")]
    private static extern bool ShowWindowAsync(IntPtr hWnd, int cmdShow);
  }

class Program
  {
    [STAThread]
    static void Main(string[] args)
    {
      //防止程序多次运行
      if (!OneInstance.IsFirst("MyTest"))
      {
        Console.WriteLine("警告:程序正在运行中! 请不要重复打开程序!可在右下角系统栏找到!");
        return;
      }
      Console.WriteLine("正在运行中");
      Console.ReadLine();
    }
  }
  public static class OneInstance
  {
    ///<summary>
    ///判断程序是否正在运行 
    ///</summary>
    ///<param name="appId">程序名称</param>
    ///<returns>如果程序是第一次运行返回True,否则返回False</returns>
    public static bool IsFirst(string appId)
    {
      bool ret = false;
      if (OpenMutex(0x1F0001, 0, appId) == IntPtr.Zero)
      {
        CreateMutex(IntPtr.Zero, 0, appId);
        ret = true;
      }
      return ret;
    }
    [DllImport("Kernel32.dll", CharSet = CharSet.Auto)]
    private static extern IntPtr OpenMutex(
      uint dwDesiredAccess, // access 
      int bInheritHandle,  // inheritance option 
      string lpName     // object name 
      );
    [DllImport("Kernel32.dll", CharSet = CharSet.Auto)]
    private static extern IntPtr CreateMutex(
      IntPtr lpMutexAttributes, // SD 
      int bInitialOwner,            // initial owner 
      string lpName              // object name 
      );
  }