Sometimes we need to check the application instance running status.

var isExists = System.Diagnostics.Process.GetProcessesByName(System.IO.Path.GetFileNameWithoutExtension(System.Reflection.Assembly.GetEntryAssembly().Location)).Count() > 1;

If you want to kill the currently loading process instantly application process, you can use below code.

if (System.Diagnostics.Process.GetProcessesByName(System.IO.Path.GetFileNameWithoutExtension(System.Reflection.Assembly.GetEntryAssembly().Location)).Count() > 1) System.Diagnostics.Process.GetCurrentProcess().Kill();

You need to add a reference to System.Core.dll for the .Count() extension method. Alternatively, you can use the .Length property.

Constants:

• Classes and structs can declare constants as members.
• Constant fields or variables must be assigned a value at the time of declaration and after that they cannot be modified.
• By default constant is static and we cannot change the value of a const variable throughout the entire program.
• Constants can be marked as public, private, protected, internal, or protected internal access modifiers.

Readonly:

• The readonly keyword is a modifier, which we can use on fields.
• A readonly field can be initialized either at the time of declaration or with in the constructor of same class.
• We can change readonly field value during runtime or we can assign it at run time but only through the non-static constructor.

Static:

• The static modifier can be used with classes, fields, methods, properties, operators, events, and constructors, but it cannot be used with indexers, destructors, or types other than classes.
• If the static keyword is applied to a class, all the members of the class must be static and Static methods can only access static members of same class.
• Static properties are used to get or set the value of static fields of a class.
• Static constructor can’t be parametrized. Access modifiers can not be applied on Static constructor, it is always a public default constructor which is used to initialize static fields of the class.

Media Access Control (MAC) address is a unique identifier assigned to most network adapters or network interface cards (NICs) by the manufacturer for identification and used in the Media Access Control protocol sub-layer. If assigned by the manufacturer, a MAC address usually encodes the manufacturer’s registered identification number. It also be known as an Ethernet Hardware Address (EHA).

In this article, I will demonstrate how to get system MAC address using C#.

public string GetMACAddress()
{
    var macAddress = string.Empty;
    NetworkInterface[] onjNI = NetworkInterface.GetAllNetworkInterfaces();
    foreach (NetworkInterface adapter in onjNI)
    {
        if (string.IsNullOrEmpty(macAddress))
        {
           IPInterfaceProperties objIP = adapter.GetIPProperties();
           macAddress = adapter.GetPhysicalAddress().ToString();
 
           if(!string.IsNullOrEmpty(macAddress))
           {
               break;
           }
        }
    }
  return macAddress;
 }