New Feature in C Sharp 7.0

Pattern Matching: Patterns are introduced in 7.0.

We can perform Pattern on Any Data Type.

We can also extract a value from an expression.

We can do Pattern matching in Two Cases which is useful for us.

            Using the is expression.

            Using the switch statement.

Using is expression:

‘is’ Pattern Matching

Using this we can assign to a variable.

Before C#7.0

class Program

    {

        public void GetDetails(dynamic a)

        {

            if (a is Employee) {

                var c = a as Employee;

                Console.WriteLine(c.Empid);

            }

            else if (a is Student) {

                var c = a as Student;

                Console.WriteLine(c.StudentId);

                Console.ReadLine();

            }

        }

        static void Main(string[] args) {

            dynamic a = new Student();

            a.StudentId = 1;

            Program obj = new Program();

            obj.GetDetails(a);

        }

    }

    class Employee {

        public int Empid { get; set; }

    }

    class Student{

        public int StudentId { get; set; }

    }

Output:

After C# 7.0

class Program

    {

        public void GetDetails(dynamic a)

        {

            if (a is Employee emp)

                Console.WriteLine(emp.Empid);

            if (a is Student student)

                Console.WriteLine(student.StudentId);

                Console.ReadLine();

        }

        static void Main(string[] args) {

            dynamic a = new Student();

            a.StudentId = 1;

            Program obj = new Program();

            obj.GetDetails(a);

        }

    }

    class Employee {

        public int Empid { get; set; }

    }

    class Student{

        public int StudentId { get; set; }

    }

Using the switch statement.

class Program

    {

        public void GetDetails(dynamic a)

        {

            switch (a)

            {

                case Employee emp:

                    Console.WriteLine(emp.Empid);

                    Console.ReadLine();

                    break;

                case Student student:

                    Console.WriteLine(student.StudentId);

                    Console.ReadLine();

                    break;

            }

        }

        static void Main(string[] args) {

            dynamic a = new Student();

            a.StudentId = 1;

            Program obj = new Program();

            obj.GetDetails(a);

        }

    }

    class Employee {

        public int Empid { get; set; }

    }

    class Student{

        public int StudentId { get; set; }

    }

Output:

Switch Statement with When Condition

class Program

    {

        public void GetDetails(dynamic a)

        {

            switch (a)

            {

                case Employee emp:

                    Console.WriteLine(emp.Empid);

                    Console.ReadLine();

                    break;

                case Student student when student.StudentId==1:

                    Console.WriteLine(student.StudentId);

                    Console.ReadLine();

                    break;

                case Student student when student.StudentId == 2:

                    Console.WriteLine(student.StudentId);

                    Console.ReadLine();

                    break;

                case Student student when student.StudentId == 3:

                    Console.WriteLine(student.StudentId);

                    Console.ReadLine();

                    break;

            }

        }

        static void Main(string[] args) {

            dynamic a = new Student();

            a.StudentId = 3;

            Program obj = new Program();

            obj.GetDetails(a);

        }

    }

    class Employee {

        public int Empid { get; set; }

    }

    class Student{

        public int StudentId { get; set; }

    }

Output: