C# – Structure, Delegate and Interface



Structure same as class to encapsulate data and code but one major difference, its uses stack memory, and act as customized type. Can not inherit because structure is the value type. Initialize the variables inside the structure shows compiler error “cannot have instance field initializers in structs”. However variable ‘const‘ keyword able to initialize.

public struct structVsClass


//public int myStructFiled = 100; //compiler error : cannot have instance field initializers in structs

public const string strucField = " 1. Structure can not be inherited. Because, structure is the value type using stack memory. \r\n 2. structure field even with public modifier with ‘const’ keyword can not be accessed in instance, but accessible within the structure member. \r\n";

public string structProperty


get { return strucField; } set { value = strucField; }




Delegate hold signature of the method, instantiate either named (method with same signature initialized with delegate instance) or anonymous (delegate instance directly initialized with anonymous method of same signature with ‘delegate‘ keyword) , type safe.

delegate int delegateSignature(int j, int i);

public class methodInSameSignature


public int multiplication(int j, int i)


return i * j;


public int add(int i, int j)


return i + j;



class Program


static void Main(string[] args)


methodInSameSignature mSS = new methodInSameSignature();

delegateSignature[] delegateInstance = {mSS.multiplication, mSS.add};

delegateSignature anonymouseDelegate = delegate(int i, int j)


return Math.Max(i,j);


foreach( delegateSignature ds in delegateInstance)


Console.WriteLine("Result of {0} is {1} .\r\n" , ds.Method.Name, ds(1, 1000).ToString());


Console.WriteLine("Result of {0} is {1} .\r\n" , anonymouseDelegate.Method.Name, anonymouseDelegate(999, 1000).ToString());





Interface also hold signature of the method, property, event and indexers , enable class designer. Can not instantiate directly it should implemented through class. Interface can be inherit from another inteface. Best example class with list value inherit using IEnumerable , IComparable


public class List<T> : IList<T>, ICollection<T>,

IEnumerable<T>, IList, ICollection, IEnumerable


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