Any Reason to Use Auto-Implemented Properties Over Manual Implemented Properties

Any reason to use auto-implemented properties over manual implemented properties?

It doesn't grant you anything extra beyond being concise. If you prefer the more verbose syntax, then by all means, use that.

One advantage to using auto props is that it can potentially save you from making a silly coding mistake such as accidentally assigning the wrong private variable to a property. Trust me, I've done it before!

Your point about auto props not being very flexible is a good one. The only flexibility you have is by either using private get or private set to limit scope. If your getters or setters have any complexity to them then the auto props are no longer a viable option.

What is the advantage of using auto-implemented properties with the default access, instead of using public fields?

The main advantages are:

1. Future-proofing your API - If you later need logic in the getter or setter, your public API doesn't change.
2. Data binding - Most data binding frameworks only work against Properties, not Fields.

what is the exact use of auto implemented properties

Having a field inside a class is not a good idea. using properties allows you to encapsulate your data better. and when you just want to have a field accessible without any logic in you class then you can use automatic properties.

there are many scenarios that using a field inside your class makes things go wrong and harder as your software evolve.

for example: assume you have

public class C
{
    public int Value;
}

in your code base.

then suddenly you realize that Value can not be set to zero. Then you have to make Value private and provide a SetValue() and GetValue() method. This is easy. but wait, how you gonna handle all other codes that relies on Value now?

but think about this one

public class C
{
    public int Value { get; set; }
}

now it just needs a backing field like _value and implementing the setter and getter.

Why are C# auto-implemented properties public?

You are correct that auto-implemented properties that simply expose a backing field are not much of a gain over a public field.

As Alan Kay said:

But most people who use setters simply use them to simulate direct assignments to interior variables, and this violates the spirit and intent of real OOP.

However, there is an advantage to an auto-implemented property over a public field, and that is that it's a non-breaking change to later revise the implementation. If you have a public field, and code outside your class manipulates that public field, you can't change it to a private field in a future version of the class, or else any other code that touches that field will have to be recompiled. By contrast, once you have a public property, you can revise the implementation of that property in a future version, and client classes can continue using it with zero changes.

So it's useful to use auto-implemented properties for properties that right now would have trivial getter and setter implementations, but that may have more complex implementations in the future.

Non-changed value and auto-implemented properties

You would use that check when you implement INotifyPropertyChanged
(You want to fire an event only when the value of the property actually changes, not simply when the setter is called.)

Auto-Implemented Properties c#

A public automatic property is not the same as a public field, they are not binary compatible. If you implement a public field and later on want to add some logic, you will have to change it into a property and thereby introduce a breaking change (because of the binary incompatibility). This is the reason why many conventions state that you should never expose public fields but rather use properties.

So, automatic properties are just a convenient starting point for any simple non-private class value member, allowing one to add logic later on while keeping binary compatibility.

Do auto implemented properties use private constructors for their initialization

This piece of code is using object initializer syntax in GetSampleProducts static method.
Object initializers can be used only on types with parameterless constructor, because it's all about syntactic sugar.
This

var p = new Product { Name="West Side Story", Price = 9.99m }

is really translated into this under the hood

var p = new Product();
p.Name = "West Side Story";
p.Price = 9.99m;

It means parameterless constructor is required for var p = new Product(); call. And it will be actually called for each item before the properties are set.

Constructor is private, but as far as GetSampleProducts is inside Product type, it can access Product private members. If you try the same syntax outside of this class it will fail.

So, this

You now have a private parameterless constructor for the sake of the new property-based initialization.

Actually means that constructor isn't used for auto-implemented properties here, it's required for property-based initialization (this term means object initializer), and if you remove it, you will get compilation errors.

Does auto implemented properties have an implied set?

This is a newly introduced feature in C# 6.0. See the C# 6.0 Language specification, section 10.7.3 Automatically implemented properties:

If the auto-property has no set accessor, the backing field is
considered readonly (§10.5.2). Just like a readonly field, a
getter-only auto-property can also be assigned to in the body of a
constructor of the enclosing class. Such an assignment assigns
directly to the readonly backing field of the property.

(Emphasis mine)

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