[RESOLVED] prevent instance of application

[daimous]

hi guys!! is there anyway for me to prevent any other intance of my windows application to run? cause i can run 2 or more of my windows application which i dont want to happen. thans in advance guys!

[jmcilhinney]

http://msdn.microsoft.com/msdnmag/is...09/NETMatters/

[daimous]

I come up the code below but still I can run another instance of my apps. btw, I call that method under Form_load. can you help me to figure out whats wrong...

        public void chk_instance()
        {
            string mutexName = Assembly.GetEntryAssembly().FullName.ToString();
            bool grantedOwnership;
            Mutex SingleInstanceMutex = new Mutex(true, mutexName,out grantedOwnership);
            if (! grantedOwnership)
            {
                MessageBox.Show("Another instance of this application is open", "BCMD", MessageBoxButtons.OK, MessageBoxIcon.Error);
                this.Close();
            }
        }

[ComputerJy]

Try this

        static bool running = false;
        /// <summary>
        /// The main entry point for the application.
        /// </summary>
        [STAThread]
        static void Main()
        {
            if (!running)
            {
                running = true;
                Application.EnableVisualStyles();
                Application.SetCompatibleTextRenderingDefault(false);
                Application.Run(new Form1());
            }
        }

[Pasvorto]

I was under the impression that you could set the "single instance" switch in the project properties window.

[ComputerJy]

I was under the impression that you could set the "single instance" switch in the project properties window.

That option exists only in VB2005

[Pasvorto]

Oh, my bad.

[daimous]

does VC#2005 has that option? i've tried to look at it but i haven't seen that option.

[jmcilhinney]

I come up the code below but still I can run another instance of my apps. btw, I call that method under Form_load. can you help me to figure out whats wrong...

        public void chk_instance()
        {
            string mutexName = Assembly.GetEntryAssembly().FullName.ToString();
            bool grantedOwnership;
            Mutex SingleInstanceMutex = new Mutex(true, mutexName,out grantedOwnership);
            if (! grantedOwnership)
            {
                MessageBox.Show("Another instance of this application is open", "BCMD", MessageBoxButtons.OK, MessageBoxIcon.Error);
                this.Close();
            }
        }

The link I posted specifically places the code to prevent multiple instances in the Main method.

[jmcilhinney]

I created a new project, edited the Main method to the following and voila.

using System;
using System.Collections.Generic;
using System.Windows.Forms;

namespace SingleInstanceTest
{
    static class Program
    {
        /// <summary>
        /// The main entry point for the application.
        /// </summary>
        [STAThread]
        static void Main()
        {
            string mutexName = "3af65962-66bf-4135-bc5a-b0f986d8e995";
            bool grantedOwnership;
            System.Threading.Mutex singleInstanceMutex = new System.Threading.Mutex(true, mutexName, out grantedOwnership);

            try
            {
                if (grantedOwnership)
                {
                    Application.EnableVisualStyles();
                    Application.SetCompatibleTextRenderingDefault(false);
                    Application.Run(new Form1());
                }
            }
            finally
            {
                singleInstanceMutex.Close();
            }
        }
    }
}

[daimous]

Sorry to ask JM but i dont have an idea where to place your code. Is

static void Main()

is automatically generated when i create a project or i need to hard-code it manually?

[jmcilhinney]

Yes, the Main method is automatically generated. As you can see from the code it is a member of the Program class. The Program class is declared in the Program.cs code file.

[daimous]

Thanks! it is working now.