C# – Instance and Static

Instance and Static

Instance members

• Data and function members that operate on the instance eg ints ToString() is a instance member of Integer class
• By default members in a type/class are instance members

Static Members

• Don’t operate on the instance of the type
• Operate on the type itself

Example

using System;

namespace Rextester
{
    public class Program
    {
        public static void Main(string[] args)
        {
            Panda p1 = new Panda ("Pan Dee");
            Panda p2 = new Panda ("Pan Dah");
            
            Console.WriteLine(p1.Name);
            Console.WriteLine(p2.Name);
            Console.WriteLine(Panda.Population);
            

        }
    }
    
    public class Panda
    {
        //instance field
        public string Name;
        
        //static field
        //set to all Panda instances
        public static int Population;
        
        //Constructor
        public Panda (string n)
        {
            //Assign the instance field
            Name = n;
            
            //Increment the static Population field
            Population = Population + 1;
        }
    }
}

Static Class
– all its members must be static