C# Propertie Implementation, Types, Examples, and Best Practices

When we access the value of the FirstName property then we get an error like.

We can create a write-only property when we don't define a get accessor.

Assign Values to Properties on Object Creation

We can also assign values to properties when we are creating an object of the class. For example when we create a Person class object then we can assign a Name and Age property to the person object.

Person objPerson = new Person()
{
    Name = "Sandeep Singh",
    Age = 24
};

Properties of objects are a block defined by curly braces and in the block, each property will be separated by a comma.

Validate Property Value

We can validate a value of a property before it's set to a variable; in other words, we can check a value to be assigned to a private field and if it is correct then it will be assigned to the private field, otherwise it will give an error.

Suppose you are a citizen of India and participate as a voter in a parliament election so your age should be greater than or equal to 18 otherwise, you can't vote. To implement this function we have a Voter class and that class has an Age property. The Age property can have a value greater than or equal to 18 otherwise it will show 0 for the age with a message. Our Voter class is.

using System;

namespace PropertyExample
{
    public class Voter
    {
        private int mAge = 0;
        public int Age
        {
            get
            {
                return mAge;
            }
            set
            {
                if (value >= 18)
                {
                    mAge = value;
                }
                else
                {
                    Console.WriteLine("You are not eligible for voting");
                }
            }
        }
    }
}

Now create an executable program by which we assign an age value of a Voter.

using System;

namespace PropertyExample
{
    class Program
    {
        static void Main(string[] args)
        {
            Voter objVoter = new Voter();
            Console.WriteLine("Please enter your age");
            objVoter.Age = Convert.ToInt32(Console.ReadLine());
            Console.WriteLine("Your age is: {0} years", objVoter.Age);
            Console.ReadKey();
        }
    }
}

Now we enter a value less than 18 and then we get a message with 0 years.

In the output screen above we get a message from the set accessor and the value isn't set in the private field so we get a default value of the private field that we already set to 0. Don't be confused by the message and return value. Here set is not returning a value. It is just printing a message on the console before the get accessor calls the Age property. The following picture shows the message shown before calling the get accessor.

If we use a value greater than or equal to 18 then we get the private field value without a message.

Use of Property as a method

We can also use a property instead of a method that has one parameter and a return value because we can define custom logic in the get and set accessors.

Suppose we have a rule for a student that when a student gets marks greater than or equal to 80 then they get 5 bonus marks and when they get marks greater than or equal to 70 but less than or equal to 79 then they get 2 bonus marks. So we define logic in the get accessor that adds marks depending on the student's original marks and thereafter the total marks (original marks + bonus marks) of the student will be returned.

using System;

namespace PropertyExample
{
    public class Student
    {
        private int mMarks = 0;

        public int Marks
        {
            get
            {
                if (mMarks >= 80)
                {
                    mMarks += 5;
                }
                else if (mMarks <= 79 && mMarks >= 70)
                {
                    mMarks += 2;
                }
                return mMarks;
            }
            set
            {
                mMarks = value;
            }
        }
    }
}

Now create a program by which we can input student marks.

using System;

namespace PropertyExample
{
    class Program
    {
        static void Main(string[] args)
        {
            Student objStudent = new Student();
            Console.WriteLine("Please enter your marks");
            objStudent.Marks = Convert.ToInt32(Console.ReadLine());
            Console.WriteLine("Your marks are: {0} marks", objStudent.Marks);
            Console.ReadKey();
        }
    }
}

Now we enter more than 80 marks and get the total marks with a bonus.

Auto mapped property

We can also create an auto-mapped property. When we create an auto-mapped property then we don't need define to the local private field in get and set accessors. For example, we have an employee class that has two properties, one in EmployeeId and another in Name. To define these properties we don't need to create a private field for these two properties and directly declare it.

namespace PropertyExample
{
    public class Employee
    {
        public int EmployeeId { get; set; }
        public string Name { get; set; }
    }
}

Now we access Employee class property in the executable program.

using System;

namespace PropertyExample
{
    class Program
    {
        static void Main(string[] args)
        {
            Employee objEmployee = new Employee()
            {
                EmployeeId = 1001,
                Name = "Sandeep"
            };
            Console.WriteLine("Employee Id is :{0} and Employee Name is :{1}", objEmployee.EmployeeId, objEmployee.Name);
            Console.ReadKey();
        }
    }
}