What is differance between int _a and int a

Question

i try lot of googling but unablre to get answer

vaibhav bhargav · Answer

@valpessam thanks for help

Sam Hobbs · Answer

Use of a leading underscore is a convention in C and C++ to indicate something that the compiler uses. There is nothing in the C and C++ languages that prevents anyone from using a leading underscore (such as in _a) but the compiler developers suggest not to. It is not uncommon however for programmers to ignore that advice. So why am I talking about C and C++ when your question is about C#? Because the C# language is very much like C++. There are many variations used for making a variable's name unique; one way is to use the leading underscore. There is absolutely nothing that requires use of a leading underscore but it is one of very many alternatives that some developers use. In C++ Microsoft uses m_ as the prefix for members of a class. Some developers might use my. I wish someone would design a better way of doing it but the syntax of a solution is not simple and obvious.

Vulpes · Answer

Incidentally you'll sometimes see 'automatic' properties used. For example this is the equivalent of the code in my first post using an automatic property: class MyClass { public int A { get; set; } } The difference is that the compiler generates the private field for you and places the appropriate code in the get and set accessors. The field is given a compiler generated name and can't be accessed directly even from code within the class itself; you always have to access it via the property.

Vulpes · Answer

Properties are a way of shielding data from code outside the class. The data cannot be accessed directly but only through the property which can make sure that you don't assign values which are invalid carry out subsidiary calculations and so forth. Suppose for example that you wanted '_a' to only be assigned values of between 0 and 9 inclusive. You could achieve that with the following property: class MyClass { int _a; public int A { get { return _a; } set { if (value 9) throw new ArgumentException(Value must be between 0 and 9); _a = value; } } } For this reason properties are sometimes called 'smart fields'.

vaibhav bhargav · Answer

thx vulpes pls can u explain examle as how it is useful(making public with get set) and when used i seen it in many code snippet

Vulpes · Answer

In C# it's possible for a variable to begin with an underscore as well as a letter. So _a and a are different variables. It's common when declaring private fields in a class to precede the field name with an underscore and then expose it via a public property which begins with an uppercase letter. For example: class MyClass { int _a; public int A { get {return _a; } set { _a = value; } } }