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C# Intermediate C# Polymorphism Virtual Properties

Nick Martini
Nick Martini
12,846 Points
Posted by Nick Martini
Nick Martini
12,846 Points

What is the purpose of the "=>" operator in this code challenge?

Within the SequenceDetector class, the Description property is being assigned an empty string by using the "=>" operator.

I have never seen this used before in this way. I have always seen properties assigned values by simply using the "=" operator instead.

What are the differences in these two assignments?

RepeatDetector.cs 
namespace Treehouse.CodeChallenges
{
    class RepeatDetector : SequenceDetector
    {
        public override bool Scan(int[] sequence)
        {
            if(sequence.Length < 2)
            {
                return false;
            }

            for(int i = 1; i < sequence.Length; ++i)
            {
                if(sequence[i] == sequence[i-1])
                {
                    return true;
                }
            }

            return false;
        }
    }
}
SequenceDetector.cs 
namespace Treehouse.CodeChallenges
{
    class SequenceDetector
    {
        public string Description => "";

        public virtual bool Scan(int[] sequence)
        {
            return true;
        }
    }
}

1 Answer

Steven Parker
Steven Parker
231,248 Points
Steven Parker
Steven Parker
231,248 Points

That's an "expression-bodied member", not an assignment.

An assignment would create a local field variable, but this creates a property with a custom getter. It's essentially equivalent to this:

public string Description
{
    get { return ""; }
}

This is one of several new features added to C# 6. If you're not still learning C# for the first time, you might want to take a look at What's New in C# 6.