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Different writing styles about set and get methods

My question about set and get methods..
Although I know how to use and why it is using for, I cant understand main differences between these using styles...
public string a{get;set;}
public string a
{
get{return a;}
set{a=value;}
}

The first form is Auto implemented properties in C#
In C# 3.0 and later, auto-implemented properties make
property-declaration more concise when no additional logic is required
in the property accessors.
The second form (although incorrect) in current form requires a backing field explicitly defined and you can put explicit code for setting and reading the values.
Second form can be like:
private string _a; // a backing field
public string a
{
get
{
return _a;
}
set
{
if (a != null) //some validation
_a = value;
else
_a = string.Empty;
}
}
(Currently your second form of property would cause a stackoverflow exception since it will enter in an infinite loop)

If you want to wite less code, use the first form, called auto property. Behind the scene, the compiler will create the backing field for you.
If you have some procesing in the property, use the standard way
public string A{get;set;} //Auto property
public string A
{
get{return a;}`
set{
//Do some check-Processing
if(value != null)
a=value;
}
}

The first one will generate an implicit field your values will be written to and read from. These are called "auto implemented properties". Whereas in the second, you explicitly name the fields your property will write to and read from. From MSDN:
In C# 3.0 and later, auto-implemented properties make property-declaration more concise when no additional logic is required in the property accessors. They also enable client code to create objects. When you declare a property as shown in the following example, the compiler creates a private, anonymous backing field that can only be accessed through the property's get and set accessors.
Your implementation
public string a
{
get{return a;}
set{a=value;}
}
will cause a StackoverflowException as you are calling a recursively in the get-accessor.
Change it to
private string a;
public string A{
get{ return a; }
set{ a = value; }
}

Let's take an example :
private string _chars;
public string Chars
{
get { return _chars; }
set
{
DoSomeThingSpecialWhenEdited();
_chars = value;
}
}
Can give you a choice to trigger DoSomeThingSpecialWhenEdited or not by setting _chars or Chars
Otherwise, the two are equivalent (Note that the latter is infinite loop) .

When to use get and set in C# class declaration [duplicate]

This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
Difference between Property and Field in C# .NET 3.5+
What's the difference between using
public string Username { get; set; }
and using
public string Username;
I have always been using the first one, but wanted to understand if there is any difference between the two, and scenarios when one should prefer over the other.

public string Username { get; set; }
is a Property.
while
public string Username;
is a Public variable.
For more comparison,
Reflection works differently on variables vs. properties, so if you rely on reflection, it's easier to use all properties.
You can't databind against a variable.
Changing a variable to a property is a breaking change.
Other link
Properties vs. Public Variables

One thing you can do with properties that you can't do with fields is limit visibility for either setter or getter:
public string MyProperty { get; private set; }
Something I use quite a lot.
And something (more powerful) you can't do with fields is define them inside an interface. Suppose you want an interface that requires implementing classes to have a certain property:
public interface MyInterface
{
string MyProperty { get; }
}
Note that you do not need to have a setter here. It is entirely up to implementing classes to determine how they should set MyProperty.

Here is a very small example of one way you could use a string property over simply using a string.
Say you have a private variable called:
private string _name;
Now lets say you wanted to make that string read only? In other words, you can't change the value. You could use the following:
public string Name
{
get { return _name; }
}
It can allow you to control access to that value. Alternatively, you can have it so that that variable can only be write only doing the following:
public string Name
{
set { _name = value; }
}
Now if you put it together, it will allow you to set to value or simply get the value. See the following:
public string Name
{
get { return _name; }
set { _name = value; }
}
You may be wondering what the point of that is since it looks like you can do the same thing with a regular string, well of course but this controls direct access to the _name variable from outside classes that aren't derived from said class.
Now what if you wanted to control how that value is set? What if you want to do some calculation or perhaps you wanted to add a prefix or suffix to that value? You do the following:
public string Name
{
get
{
return _name;
}
set
{
if (value.ToLower() == "bilbo")
_name = "Bilbo Baggins";
}
}
Now, if you set the Name property of the class to bilbo, the value of _name will be set to Bilbo Baggins as opposed to if you set the property to Amy, the _name variable will contain simply, amy.
You can do this to guarantee that whatever value that the property is set to is automatically upper or lowercase, or perhaps you can do some validation on the value or something of that sort.
I hope this explains the uses of properties and how they can be useful without making it too complicated.

Properties provide you with more flexibility, especially in .NET. C# shows bias toward properties, so keep that in mind. However, as a general rule, use accessors/mutators when getting or setting needs "processing" or an accompanying action. Use fields for holding values. E.g.,
public class Name
{
public string First;
public string Last;
public string Full{ get { return this.First + " " + this.Last; } }
}

How to make a property required in c#?

I have requirement in a custom class where I want to make one of my properties required.
How can I make the following property required?
public string DocumentType
{
get
{
return _documentType;
}
set
{
_documentType = value;
}
}

If you mean "the user must specify a value", then force it via the constructor:
public YourType(string documentType) {
DocumentType = documentType; // TODO validation; can it be null? blank?
}
public string DocumentType {get;private set;}
Now you can't create an instance without specifying the document type, and it can't be removed after that time. You could also allow the set but validate:
public YourType(string documentType) {
DocumentType = documentType;
}
private string documentType;
public string DocumentType {
get { return documentType; }
set {
// TODO: validate
documentType = value;
}
}

.NET 7 or newer
Syntax
public class MyClass
{
public required string Name { get; init; }
}
new MyClass(); // illegal
new MyClass { Name = "Me" }; // works fine
Remarks
The required properties must declare a setter (either init or set).
Access modifiers on properties or setters cannot be less visible than their containing type, as they would make impossible to initialize the class in some cases.
public class MyClass
{
internal required string Name { get; set; } // illegal
}
Documentation
Official documentation here
Feature demo here
.NET 6 or older
See this answer

If you mean you want it always to have been given a value by the client code, then your best bet is to require it as a parameter in the constructor:
class SomeClass
{
private string _documentType;
public string DocumentType
{
get
{
return _documentType;
}
set
{
_documentType = value;
}
}
public SomeClass(string documentType)
{
DocumentType = documentType;
}
}
You can do your validation – if you need it – either in the property's set accessor body or in the constructor.

With the release of .NET 7 and C# 11 in November 2022 you can now use the required modifier this way:
public class Person
{
public Person() { }
[SetsRequiredMembers]
public Person(string firstName) => FirstName = firstName;
public required string FirstName { get; init; }
public int Age { get; set; }
}
And when you don't have the required properties it will throw an error when you try to initialize an object.
For more information refer to:
https://learn.microsoft.com/en-us/dotnet/csharp/whats-new/csharp-11#required-members
https://learn.microsoft.com/en-us/dotnet/csharp/properties#init-only

Add a required attribute to the property
Required(ErrorMessage = "DocumentTypeis required.")]
public string DocumentType
{
get
{
return _documentType;
}
set
{
_documentType = value;
}
}
For custom attribute detail Click Here

I used an other solution, not exactly what you want, but worked for me fine because I declare the object first and based on specific situation I have different values. I didnt want to use the constructor because I then had to use dummy data.
My solution was to create Private Sets on the class (public get) and you can only set the values on the object by methods. For example:
public void SetObject(string mandatory, string mandatory2, string optional = "", string optional2 = "")

This one liner works in C# 9:
public record Document(string DocumentType);
new Document(); // compiler error
new Document("csv"); // correct way to construct with required parameter
This explains how it works. In the above code, Document is the name of the class or "record". That first line of code actually defines an entire class. In addition to this solution essentially making a required DocumentType property (required by an auto implemented constructor), because it uses records, there are additional implications. So this may not always be an appropriate solution, and the C# 11 required keyword will still come in handy at times. Just using record types doesn't automatically make properties required. The above code is a special syntax way of using records that essentially has this effect as well as making the property init only and causes a deconstructor to be automatically implemented.
A better example would be using an int property instead of a string since a string could still be empty. Unfortunately I don't know of any good way to do extra validation within the record to make sure the string is not empty or an int is in range, etc. You would have to go deeper down the TOP (type driven development) rabbit hole, which may not be a bad thing. You could create your own type that doesn't allow empty strings or integers outside your accepted range. Unfortunately such an approach would lead to runtime discovery of invalid input instead of compile time. There might be a better way using static analysis and metadata, but I've been away from C# for too long to know anything about that.

C# Custom getter/setter without private variable

I learned c# recently, so when I learned to write properties, I was taught to do it like this:
public string Name { get; set; }
Auto properties are great! But now I'm trying to do something a little more complicated, so I need to write a custom pair of accessors.
private string _Name;
public string Name {
get { return _Name; }
set { _Name = value }
}
I know the compiler makes a private instance variable down in it's murky depths when one uses autos, but I'm spoiled and don't want that private variable sitting around looking pointless.
Is there a way to use custom accessors without a private variable?

Properties don't need backing variables (fields) at all. While they can be used for encapsulating simple fields you can also use them to access other data.
public Decimal GrandTotal { get { return FreightTotal + TaxTotal + LineTotal; } }
or
public string SomeStatus { get { return SomeMethodCall(); } }
If the goal is to simply encapsulate some field with a property you would need some sort of backing field if you are not using automatic properties.

The answer is No, you cannot do that.
It is because of recursion. (See line numbers 9 and 7):
Line 1 : public string Name
Line 2 : {
Line 3 : get
Line 4 : {
Line 5 : return FirstName + " " + LastName;
Line 6 : }
Line 7 : set
Line 8 : {
Line 9 : Name = value; // <-- Goes back to Line 7
Line 10 : }
Line 11 : }

No, I'm afraid not. The compiler is smart enough to make this happen for you on auto-generated properties, but with standard properties I imagine the logic behind something like that would end up getting in the way and doing more harm than good.
For example, what if I create a property like this...
public int SomeValue
{
get
{
return 0;
}
}
Would the compiler (with the feature you're looking for) create a backing private variable? Why? It doesn't need one.
Additionally, if the private value isn't created until compilation time, what are you going to reference in your code:
public string Name {
get { return _Name; }
set { _Name = value }
}
What is _Name? What if you have another value somewhere else called _Name? Then what would the compiler call the backing value for this property? What if I need two backing values? Would the compiler be smart enough for that?
public string Name
{
get
{
return string.Format("{0} {1}", _FirstName, _LastName);
}
set
{
// some parsing magic
}
}
It's been asked before, but I imagine the answer is going to continue to be "no" for the foreseeable future.
An auto-property is syntactic shorthand for simple direct member access. (And I imagine one of its driving forces was simply to try to get people to stop creating public values directly.) Properties can grow in complexity well beyond that very easily and I personally wouldn't want the compiler trying to figure out what I can easily just tell it to do.

I know this is an old question, but there is at least one other option here. I'm doing something similar to the below for my own app.
This might not exactly be for your use case, but it shows that a custom getter and setter can be used without a private instance variable. In this case, the getter and setter are shortcut or helper methods to access the Name property of the User for the Account.
We can let the value be set by doing Account.AccountUser.Name = "John Doe";, but sometimes that seems a bit clunky and it works against the idea of separation of concerns. Do we want someone using the Account class to know there's a User imbedded in it? If for some reason we don't, we now have a way to still update the User.Name even if we make AccountUser private.
In this case, AccountUser is public, but it doesn't have to be. When it's private, a Json or XML conversion utility (such as Newtonsoft) should ignore the AccountUser and show just the Name as if the Account were a flat model, instead of having multiple levels.
public class User
{
public int Id { get; set; }
public string Name { get; set; }
}
public class Account
{
public int Id { get; set; }
public User AccountUser { get; set; }
public string Name
{
get
{
return AccountUser.Name;
}
set
{
AccountUser.Name = value;
}
}
}

Getters, setters, and properties best practices. Java vs. C#

I'm taking a C# class right now and I'm trying to find out the best way of doing things. I come from a Java background and so I'm only familiar with Java best-practices; I'm a C# novice!
In Java if I have a private property, I do this;
private String name;
public void setName(String name) {
this.name = name;
}
public String getName() {
return this.name;
}
In C#, I see that there are many ways of doing this.
I can do it like Java:
private string name;
public void setName(string name) {
this.name = name;
}
public string getName() {
return this.name;
}
Or I can do it this way:
private string name;
public string Name {
get { return name; }
set { name = value; }
}
Or:
public string Name { get; set; }
Which one should I use, and what are the caveats or subtleties involved with each approach? When creating classes, I am following general best-practices that I know from Java (especially reading Effective Java). So for example, I am favoring immutability (providing setters only when necessary). I'm just curious to see how these practices fit in with the various ways of providing setters and getters in C#; essentially, how would I translate best-practices from the Java world into C#?
EDIT
I was posting this as a comment to Jon Skeet's answer but then it got long:
What about a non-trivial property (i.e., with significant processing and validation perhaps)? Could I still expose it via a public property but with the logic encapsulated in get and set? Why would/should I do this over having dedicated setter and getter methods (with associated processing and validation logic).

Pre-C# 6
I'd use the last of these, for a trivial property. Note that I'd call this a public property as both the getters and setters are public.
Immutability is a bit of a pain with automatically implemented properties - you can't write an auto-property which only has a getter; the closest you can come is:
public string Foo { get; private set; }
which isn't really immutable... just immutable outside your class. So you may wish to use a real read-only property instead:
private readonly string foo;
public string Foo { get { return foo; } }
You definitely don't want to write getName() and setName(). In some cases it makes sense to write Get/Set methods rather than using properties, particularly if they could be expensive and you wish to emphasize that. However, you'd want to follow the .NET naming convention of PascalCase for methods, and you wouldn't want a trivial property like this to be implemented with normal methods anyway - a property is much more idiomatic here.
C# 6
Hooray, we finally have proper read-only automatically implemented properties:
// This can only be assigned to within the constructor
public string Foo { get; }
Likewise for read-only properties which do need to do some work, you can use member-bodied properties:
public double Area => height * width;

If all you need is a variable to store some data:
public string Name { get; set; }
Want to make it appear read-only?
public string Name { get; private set; }
Or even better...
private readonly string _name;
...
public string Name { get { return _name; } }
Want to do some value checking before assigning the property?
public string Name
{
get { return m_name; }
set
{
if (value == null)
throw new ArgumentNullException("value");
m_name = value;
}
}
In general, the GetXyz() and SetXyz() are only used in certain cases, and you just have to use your gut on when it feels right. In general, I would say that I expect most get/set properties to not contain a lot of logic and have very few, if any, unexpected side effects. If reading a property value requires invoking a service or getting input from a user in order to build the object that I'm requesting, then I would wrap it into a method, and call it something like BuildXyz(), rather than GetXyz().

Use properties in C#, not get/set methods. They are there for your convenience and it is idiomatic.
As for your two C# examples, one is simply syntactic sugar for the other. Use the auto property if all you need is a simple wrapper around an instance variable, use the full version when you need to add logic in the getter and/or setter.

In C# favor properties for exposing private fields for get and/or set. The thie form you mention is an autoproperty where the get and set automatically generate a hidden pivot backing field for you.
I favor auto properties when possible but you should never do a set/get method pair in C#.

public string Name { get; set; }
This is simply a auto-implemented property, and is technically the same as a normal property. A backing field will be created when compiling.
All properties are eventually converted to functions, so the actual compiled implementation in the end is the same as you are used to in Java.
Use auto-implemented properties when you don't have to do specific operations on the backing field. Use a ordinary property otherwise. Use get and set functions when the operation has side effects or is computationally expensive, use properties otherwise.

Regardless of which way you choose in C# the end result is the same. You will get a backinng variable with separate getter and setter methods. By using properties you are following best practices and so it's a matter of how verbose you want to get.
Personally I would choose auto-properties, the last version: public string Name { get; set; }, since they take up the least amount of space. And you can always expand these in the future if you need add something like validation.

Whenever possible I prefer public string Name { get; set; } as it's terse and easily readable. However, there may be times when this one is necessary
private string name;
public string Name {
get { return name; }
set { name = value; }
}

In C# the preferred way is through properties rather than getX() and setX() methods. Also, note that C# does not require that properties have both a get and a set - you can have get-only properties and set-only properties.
public boolean MyProperty
{
get { return something; }
}
public boolean MyProperty
{
set { this.something = value; }
}

First let me try to explain what you wrote:
// private member -- not a property
private string name;
/// public method -- not a property
public void setName(string name) {
this.name = name;
}
/// public method -- not a property
public string getName() {
return this.name;
}
// yes it is property structure before .Net 3.0
private string name;
public string Name {
get { return name; }
set { name = value; }
}
This structure is also used nowadays but it is most suitable if you want to do some extra functionality, for instance when a value is set you can it to parse to capitalize it and save it in private member for alter internal use.
With .net framework 3.0
// this style is introduced, which is more common, and suppose to be best
public string Name { get; set; }
//You can more customize it
public string Name
{
get;
private set; // means value could be set internally, and accessed through out
}
Wish you better luck in C#

As mentioned, all of these approaches result in the same outcome. The most important thing is that you pick a convention and stick with it. I prefer using the last two property examples.

like most of the answers here, use Automatic properties. Intuitive, less lines of code and it is more clean. If you should serialize your class, mark the class [Serializable]/ with [DataConract] attribute. And if you are using [DataContract] mark the member with
[DataMember(Name="aMoreFriendlyName")]
public string Name { get; set; }
Private or public setter depends on your preference.
Also note that automatic properties require both getters and setters(public or private).
/*this is invalid*/
public string Name
{
get;
/* setter omitted to prove the point*/
}
Alternatively, if you only want get/set, create a backing field yourself

Which one should I use, and what are the caveats or subtleties involved with each approach?
When going with properties there is one caveat that has not been mentioned yet: With properties you cannot have any parametrization of your getters or setters.
For example imagine you want to retrieve a list items and want to also apply a filter at the same time. With a get-method you could write something like:
obj.getItems(filter);
In contrast, with a property you are forced to first return all items
obj.items
and then apply the filter in the next step or you have to add dedicated properties that expose items filtered by different criteria, which soon bloats your API:
obj.itemsFilteredByX
obj.itemsFilteredByY
What sometimes can be a nuisance is when you started with a property, e.g. obj.items and then later discovered that getter- or setter-parametrization is needed or would make things easier for the class-API user. You would now need to either rewrite your API and modify all those places in your code that access this property or find an alternative solution. In contrast, with a get-method, e.g. obj.getItems(), you can simply extend your method's signature to accept an optional "configuration" object e.g. obj.getItems(options) without having to rewrite all those places that call your method.
That being said, (auto-implemented) properties in C# are still very useful shortcuts (for the various reasons mentioned here) since most of the time parametrization may not be needed – but this caveat stands.