A lot of programmers are not familiar with the term immutable when it comes to software development the terminology often confuses them. I am going to try and explain it in this post.

An immutable object is an object that once it is created none of its values should change.

A simple way to do this is to only assign to the variables of that object in the constructor so that once the object is created its variables cannot be changed:

    public class GPSCoords
    {
        private readonly int longitude;
        private readonly int latitude;

        public GPSCoords(int longitude, int latitude)
        {
            this.longitude = longitude;
            this.latitude = latitude;
        }

        public int Longitude
        {
            get { return longitude; }
        }

        public int Latitude
        {
            get { return latitude; }
        }
    }

You can also achieve the same goal in .NET by making the class GPSCoords a struct:

    public struct GPSCoords
    {
        public readonly int longitude;
        public readonly int latitude;
 
        public GPSCoords2(int longitude, int latitude)
        {
            this.longitude = longitude;
            this.latitude = latitude;
        }
    }

If you have worked with the string class in the .NET framework you probably didn't realize that you were working with a immutable class. So the next time someone asks you in an interview to explain the behaviour of the string class you will be able to explain it to them. 

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