Attributes can be applied to

1. Method
2. Class
3. Assembly
4. Namespace
5. Enum

1. int[ , ] a;
   a = new int[2, 3]{{7, 1, 3},{2, 9, 6}};

2. int[ , ] a;
   a = new int[2, 3]{};

3. int[ , ] a = {{7, 1, 3}, {2, 9,6 }};

4. int[ , ] a;
   a = new int[1, 2];

5. int[ , ] a;
   a = new int[1, 2]{{7, 1, 3}, {2, 9, 6}};

String str = "She sells sea shells on the sea-shore"; 
int i;
i = str.SecondIndexOf("s");

String str = "She sells sea shells on the sea-shore"; 
int i, j;
i = str.FirstIndexOf("s"); 
j = str.IndexOf("s", i + 1);

String str = "She sells sea shells on the sea-shore"; 
int i, j;
i = str.IndexOf("s"); 
j = str.IndexOf("s", i + 1);

String str = "She sells sea shells on the sea-shore"; 
int i, j;
i = str.LastIndexOf("s"); 
j = str.IndexOf("s", i - 1);

String str = "She sells sea shells on the sea-shore"; 
int i, j;
i = str.IndexOf("S"); 
j = str.IndexOf("s", i);

namespace CuriousTabConsoleApplication
{
    class Baseclass
    { 
        int i;
        public Baseclass(int ii)
        {
            i = ii;
            Console.Write("Base "); 
        } 
    } 
    class Derived : Baseclass
    {
        public Derived(int ii) : base(ii)
        {
            Console.Write("Derived ");
        } 
    } 
    class MyProgram
    { 
        static void Main(string[ ] args)
        { 
            Derived d = new Derived(10);
        } 
    } 
}

public sample operator + ( sample a, sample b )

public abstract operator + ( sample a, sample b)

public abstract sample operator + (sample a, sample b )

public static sample operator + ( sample a, sample b )

1. Custom attribute cannot be applied to an assembly.
2. [assembly: Tested("Sachin", testgrade.Good)]
3. [Tested("Virat", testgrade.Excellent)]
   class customer { /* .... */ }
4. Custom attribute cannot be applied to a method.
5. Custom attribute cannot be applied to a class.