C# member variables / fields naming convention

Question

Hi

There is too much discussion about the class fields naming, but the major difference is this:

private int foo;

private int _foo;

Can anyone tell us, what's the latest decision about this convention?

Thank you!

Answer 1

The latest decision according to "official" Field Usage Guidelines is:

private int foo;

Field names are written by convention in camelCase.

Also read Naming Guidelines - .NET Framework General Reference

Answer 2

The "usual" naming convention is to have the underscore for the private field and the same name without the underscore for the corresponding (if any) property.

Answer 3

I certainly won't start comparing myself to Jon Skeet, but here's my take on it.

You have two situations:

1. You always prefix your field accesses with this..
2. You do not.

For each of these cases:

1. Preference, judgement call.
2. Use a prefix for private fields. I don't care what it is, but pick something and stick with it. It seems the two common ones are m_ and just _.

In either case, be consistant, like with anything.

Answer 4

Who's going to NameCon next year?

Answer 5

Here's what I've found:

"Recent" code in the .NET Framework has used both (though never in the same class, and generally the difference is across teams as a whole - WPF might use something different from Parallel FX (haven't checked if they do), but WPF blending effects would use the same as WPF text rendering).

StyleCop "suggests" using foo as a member field instead of _foo, and referencing it as this.foo inside of class members. The rationale there is:

1. Using this.memberName is clearer than memberName and
2. When using this.memberName, the _ doesn't do anything in regards to identifying the reference as a member field, because the this. already did that. Unndecessary redundancy clutters code, therefore no _ prefix.

I personally, IMO prefer _foo for two reasons that form the rationale for the other method you've observed:

1. Reducing the number of aliased names in methods
2. I can still keep parameter names with the same (exact) spelling and casing as member fields. With the only change being the underscore, it just seems clearer to me.

Answer 6

Personally I prefer _foo for a private field and Foo for a public field as follows

private string _foo;

public string Foo 
{
    get { return _foo; }
    set { _foo = value; }
}

Answer 7

We follow this, which is a summary of MS .NET practices: http://www.irritatedvowel.com/Programming/Standards.aspx

Then it would be underscore for private fields.

private int _foo;

Answer 8

Use StyleCop