Passing by value & passing by reference in C# using Reference Types

Case 1:

Both are same.

public class Program
{
        static void Main()
        {
            Employee employee;

            employee = new Employee();
            PopulateEmployee(employee);
            Console.WriteLine($"Sr.No: {employee.SrNo} & Name: {employee.Name}");

            employee = new Employee();
            PopulateEmployeeByRef(ref employee);
            Console.WriteLine($"Sr.No: {employee.SrNo} & Name: {employee.Name}");

            Console.ReadLine();
        }

        public static void PopulateEmployee(Employee employee)
        {
            //employee = new Employee();
            employee.SrNo = 1;
            employee.Name = "Ankush Jain";
        }

        public static void PopulateEmployeeByRef(ref Employee employee)
        {
            //employee = new Employee();
            employee.SrNo = 1;
            employee.Name = "Ankush Jain";
        }
}

public class Employee
{
        public int SrNo { get; set; }
        public string Name { get; set; }
}

Case 2:

Instantiation of the parameter in passing by reference actually changes the value of properties of passed argument while passing by value does not.

public class Program
{
        static void Main()
        {
            Employee employee;

            employee = new Employee();
            PopulateEmployee(employee);
            Console.WriteLine($"Sr.No: {employee.SrNo} & Name: {employee.Name}");

            employee = new Employee();
            PopulateEmployeeByRef(ref employee);
            Console.WriteLine($"Sr.No: {employee.SrNo} & Name: {employee.Name}");

            Console.ReadLine();
        }

        public static void PopulateEmployee(Employee employee)
        {
            employee = new Employee();
            employee.SrNo = 1;
            employee.Name = "Ankush Jain";
        }

        public static void PopulateEmployeeByRef(ref Employee employee)
        {
            employee = new Employee();
            employee.SrNo = 1;
            employee.Name = "Ankush Jain";
        }
}

public class Employee
{
        public int SrNo { get; set; }
        public string Name { get; set; }
}

Reference: https://stackoverflow.com/a/1293120/1273882