How do you name your private variables in C#?

Question

What is the best practice, most commonly accepted naming conventions for private variables in C#?

1. private int myInteger;
2. private int MyInteger;
3. private int mMyInteger;
4. private int _myInteger;
5. private int _MyInteger;
6. Mysterious other option

Which do you use and why? (My company is fairly new to C# and I would like to pick the most "industry accepted" method to try and get into our coding standard.)

Answer 1

The MSDN class design guidlines http://msdn.microsoft.com/en-us/library/ta31s3bc.aspx recommends option 1 - myInteger.

I have always used this style. I have a personal dislike for the _ character.

Answer 2

I use option #4 above:

private int _myInteger;

I like to have some indication of scope in my variable names, and the underscore is sufficient for that purpose. It's also quite easy to read.

Answer 3

I use the following naming scheme:

• 1st (myInteger) for local scoped variables
• 2nd (MyInteger) for public properties
• 4th (_myInteger) for private variables

Answer 4

I think the option 4 is really the most readable option. It helps you from having to do this:

public Person(string name, int age) 
{
    this.name = name;
    this.age = age;
}

It also makes all private members more noticeable. In the following example, where the heck is age coming from? Without the this qualifier it is harder to tell.

private void Method()
{
    var x = 2;
    var y = age + x;
}

This is way easier to understand:

private void Method()
{
    var x = 2;
    var y = _age + x;
}

Answer 5

First off, PascalCasing is commonly reserved for public properties, consts, methods, etc of the class. So I would skip 2 and 5.

Second, hungarian notation is discouraged in the .NET world, so (uh, I think) 3 is right out. Assuming that's what is going on with 3.

That leaves with camelCasing and _camelCasing. I typically use _camelCasing for class variables, and plain old camelCasing for variables scoped to a method or narrower. Camel casing is the accepted standard used for method arguments, protected/private variable names and variables within a method or narrower scope.

I also like to prepend with the underscore so that my private variables are grouped in my intellisense. However, I only do this for variables scoped to a type. Variables declared within a method or narrower scope I leave the underscore off. Makes it easy to keep them separate and keep less used variables together.

Answer 6

private int integer

If you get confused between member and local variables in a method scope then you probably need to refactor.

Answer 7

I wouldn't call it "my" anything!

But I'd say

class C
{
     int VariableName { get; set; }
}

quite often this is nicer than having explicit variables. If I had an explicit private variable i'd call it int _variableName;

Answer 8

I do option #4 because that's what the SSCLI looks like, but honestly I don't care that much on naming of private variable. Public is a different story.

BTW you forgot m_MyInteger

Answer 9

In C++ I tend to use _ as I switch editors a lot which doesn't allow me to see if it's private.

For C# I tend to to leave the _ away as Visual Studio allows me to see if it's private.

I tend to use the Camel Case way to do this.

Answer 10

I use 4 (private int _myInteger;) because:

private int myInteger;

This is how I name my local variables.

private int MyInteger;

This is how I name constants.

private int mMyInteger;

This is not C# style.

private int _MyInteger;

This looks strange.

Answer 11

I believe the best way to do it (in C#/.net anyway) is a combination of 2 and 6:

private int MyInteger { get; set; }

There's theoretically no variable at all here, but it looks and acts like a private instance variable. If we need to add some business logic to that value (it's a completely internal value, so we can do anything we want to it after all) then it's already 'propertyized' for us. A hot steaming cup of win!

Answer 12

with the underscore.

Bill Wagner explains why in Effective C#. But I would never name an integer myInteger, better something like _age or _length. Including the TypeName in the instance name is a horrible practice. Names should be self explanatory and since C# is Type-Safe types can be found out att all times.

Answer 13

You need to give a more specific example, but:

private int count, private int badFileCount, private static readonly int ReconnectAttemptsLimit

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Answer 14

I go by option 5: private int _MyFoo

I don't see any real competitive advantage over _myFoo though.

Answer 15

Juval Lowy's IDesign C# Coding Standard is quite popular. This standard recommends prefixing private member variables with "m_" (Option 6). That's what we do in our team.

private int m_myInteger;

Option 4 (_myInteger) is an acceptable variation of this standard.

I didn't like the MSDN recommendation (myInteger), because it makes it difficult to tell a private member from a local variable. Their recommendation, of course, solves this problem by qualifying private members with this, which seems redundant to me.

Answer 16

Use camelCasing for private variables like myInteger

Consider a preceding _ if the variable is a backup for a property to reduce confusions-
Variable _myProperty for property MyProperty

Answer 17

I have ReSharper name my variables, not only mine but everyone else does this as well. There is a great amount of consistency trough the project.