using System; using System.Collections.Generic; using System.Linq; using System.Windows.Forms; using System.Threading; namespace WindowsFormsApplication1 { static class Program { /// <summary> /// The main entry point for the application. /// </summary> [STAThread] static void Main() { Application.EnableVisualStyles(); Application.SetCompatibleTextRenderingDefault(false); bool ret; Mutex mutex = new Mutex(true, Application.ProductName, out ret); if (ret) { Application.Run(new Form1()); } else { MessageBox.Show ( " This program has been launched " , " message " , MessageBoxButtons.OK, MessageBoxIcon.Information); } } } }
Transfer from https://www.cnblogs.com/LicwStack/p/8587352.html