What does this mean ({ get; set; }) in C#?

Published on Author Code Father

So as I understand it {get; set;} is an “auto property” which just like @Klaus and @Brandon said is shorthand for writing a property with a “backing field.” So in this case:

public class Genre
{
    private string name; // This is the backing field
    public string Name // This is your property
    {
        get {return name;}
        set {name = value;}}
    }

However if you’re like me – about an hour or so ago – you don’t really understand whatproperties and accessors are, and you don’t have the best understanding of some basic terminologies either. MSDN is a great tool for learning stuff like this but it’s not always easy to understand for beginners. So I’m gonna try to explain this more in-depth here.

get and set are accessors, meaning they’re able to access data and info in private fields (usually from a backing field) and usually do so from public properties (as you can see in the above example).

There’s no denying that the above statement is pretty confusing, so let’s go into some examples. Let’s say this code is referring to genres of music. So within the class Genre, we’re going to want different genres of music. Let’s say we want to have 3 genres: Hip Hop, Rock, and Country. To do this we would use the name of the Class to create new instances of that class.

Genre g1 = new Genre(); //Here we're creating a new instance of the class "Genre"
                        //called g1. We'll create as many as we need (3)
Genre g2 = new Genre();
Genre g3 = new Genre();

//Note the () following new Genre. I believe that's essential since we're creating a
//new instance of a class (Like I said, I'm a beginner so I can't tell you exactly why
//it's there but I do know it's essential)

Now that we’ve created the instances of the Genre class we can set the genre names using the ‘Name’ property that was set way up above.

public string Name //Again, this is the 'Name' property
{ get; set; } //And this is the shorthand version the process we're doing right now 

We can set the name of ‘g1’ to Hip Hop by writing the following

g1.Name = "Hip Hop";

What’s happening here is sort of complex. Like I said before, get and set access information from private fields that you otherwise wouldn’t be able to access. get can only readinformation from that private field and return it. set can only write information in that private field. But by having a property with both get and set we’re able do both of those functions. And by writing g1.Name = "Hip Hop"; we are specifically using the set function from our Name property

set uses an implicit variable called value. Basically what this means is any time you see “value” within set, it’s referring to a variable; the “value” variable. When we write g1.Name =we’re using the = to pass in the value variable which in this case is "Hip Hop". So you can essentially think of it like this:

public class g1 //We've created an instance of the Genre Class called "g1"
{
    private string name;
    public string Name
    {
        get{return name;}
        set{name = "Hip Hop"} //instead of 'value', "Hip Hop" is written because 
                              //'value' in 'g1' was set to "Hip Hop" by previously
                              //writing 'g1.Name = "Hip Hop"'
    }
}

It’s Important to note that the above example isn’t actually written in the code. It’s more of a hypothetical code that represents what’s going on in the background.

So now that we’ve set the Name of the g1 instance of Genre, I believe we can get the name by writing

console.WriteLine (g1.Name); //This uses the 'get' function from our 'Name' Property 
                             //and returns the field 'name' which we just set to
                             //"Hip Hop"

and if we ran this we would get "Hip Hop" in our console.

So for the purpose of this explanation I’ll complete the example with outputs as well

using System;
public class Genre
{
    public string Name { get; set; }
}

public class MainClass
{
    public static void Main()
    {
        Genre g1 = new Genre();
        Genre g2 = new Genre();
        Genre g3 = new Genre();

        g1.Name = "Hip Hop";
        g2.Name = "Rock";
        g3.Name = "Country";

        Console.WriteLine ("Genres: {0}, {1}, {2}", g1.Name, g2.Name, g3.Name);
    }
}

Output:

"Genres: Hip Hop, Rock, Country"

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Categories C#