Are variable prefixes (“Hungarian notation”) really necessary anymore? [closed]

问题

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Closed 6 years ago.

Since C# is strongly typed, do we really need to prefix variables anymore?

e.g.

iUserAge
iCounter
strUsername

I used to prefix in the past, but going forward I don't see any benefit.

回答1:

Are variable prefixes ( Hungarian ) really necessary anymore?

NO!

In fact, Microsoft's own style guidelines (where the practice originated) now recommend against it. In particular, see the section on General Naming Conventions, which includes the following text (in bold type, no less):

Do not use Hungarian notation.

回答2:

The only places I see fit to bend the standards and prefix variables:

• control names: txtWhatever - and I see I'm not the only one. The nice thing is that you can come up with stuff like lblName next to txtName, and you don't need to go into the NameLabel/NameTextBox direction.

• class member variables: _whatever. I've tried both m_ and no prefix at all and ended up with simple underscore. m_ is more difficult to type and having no prefix becomes confusing sometimes (especially during maintenance, I know all of you know their code by heart while writing it)

I didn't find any consistent situation where prefixing a variable with its type would make the code more readable, though.

EDIT: I did read the Microsoft guidelines. However I consider that coding styles are allowed to evolve and/or be "bent", where appropriate. As I mentioned above, I found using underscore prefix useful by trial and error, and is certainly better than using this.whatever everywhere in the code.

Supporting the "evolving" theory - back in .NET 1.x when Microsoft released coding guidelines, they advised using Camel casing for everything, even constants. I see now they've changed and advise using Pascal case for constant or public readonly fields.

Furthermore, even .NET Framework class library is currently full of m_ and _ and s_ (try browsing the implementation with the Reflector). So after all, it's up to the developer, as long as consistency is preserved across your project.

回答3:

If Hungarian means "prefix with a type abbreviation" such as uCount or pchzName, then I would say this practice is bad and thankfully seems to be fading from common use.

However, I do still think that prefixes are very useful for scope. At my studio we use this convention for prefixing variables :

i_  // input-only function parameter (most are these)
o_  // output-only function parameter (so a non-const & or * type)
io_ // bidirectional func param
_   // private member var (c#)
m_  // private member var (c++)
s_  // static member var (c++)
g_  // global (rare, typically a singleton accessor macro)

I've found this to be very useful. The func param prefixes in particular are useful. Way down inside a function you can always tell where that var came from at a glance. And typically we will copy the var to another when we want to modify it or change its meaning.

So in short: prefixes for types are unnecessary with modern tools. The IDE takes care of identifying and checking that stuff for you. But scope-based prefixes are very useful for readability and clarity.

There are also fun side benefits like with Intellisense. You can type i_ ctrl-space and get all the input params to the func to choose from. Or g_ ctrl-space to get all your singletons. It's a time-saver.

回答4:

Nope. Did we ever need to?

回答5:

Hungarian notation is ugly. The only exception is with interfaces, where most people think it's acceptable.

Linus sums it up well: "Encoding the type of a function into the name (so-called Hungarian notation) is brain damaged - the compiler knows the types anyway and can check those, and it only confuses the programmer"

回答6:

No. Hungarian Notation just adds unnecessary noise to code and is redundant with compiler type checking.

回答7:

Yes, if Hungarian notation were used as it was originally meant, instead of as implemented by Microsoft. Much like the example above, which shows text boxes and corresponding labels as lblWhatever, txtWhatever. Use it to define the use of the variable, not the type. It can provide information to know that your number is moneyTotal, which tells me more than just the data type.

But, as commonly used? No.

回答8:

Prefixes are a leftover from the VB (and older!) days when Hungarian Notation was king. That is no longer the case, though the C# community does mandate things like using a prefix of Capital I for interfaces (e.g. ILoadable).

The current Microsoft Guidelines are here.

回答9:

Hungarian notation is no longer needed to identify data types like in your string example, but it still can be useful for identifying characteristics of variables in other ways. Here's a good article that talks about useful ways of using the Hungarian notation: http://www.joelonsoftware.com/articles/Wrong.html

Here's an excerpt

"In Simonyi’s version of Hungarian notation, every variable was prefixed with a lower case tag that indicated the kind of thing that the variable contained.

For example, if the variable name is rwCol, rw is the prefix.

I’m using the word kind on purpose, there, because Simonyi mistakenly used the word type in his paper, and generations of programmers misunderstood what he meant."

He also uses an example of identifying strings prefixed with an 's' or a 'u' to identify if they are secure to print out or not, so that a statement like print(uSomeString); can easily be identified as wrong.

回答10:

Most of the arguments I see against Hungarian notation mention that modern editors and IDEs are perfectly capable of giving you all the information you need to know about every identifier. Fair enough.

But what about printed code? Don't you carry out code reviews or walkthroughs on paper? Don't you use printed code for training purposes? Don't you use code snippets for online help? Hungarian notation is extremely valuable in these occasions.

I keep using (some sort of) Hungarian notation in all my code. I find its absence ugly and lacking in information.

回答11:

I personally don't anymore, however you will still people argue to prefix for scope.

I go with Microsoft and use their Capitalization Styles for all naming conventions. The entire "Design Guidelines for Class Library Developers" section, which that link is a part of, is pure gold, in my opinion.

Additionally, I love the "Framework Design Guidelines" book from Addison Wesley. It covers all of these guidelines with annotations from Microsoft team members on to why they recommend what they are proposing and how it is adopted within the organization.

回答12:

Well, to counter, I'd say - it depends. I'm personally against them, but it comes down to your team. Each team should be responsible for developing their own set of guidelines. Hopefully that doesn't include so-called Hungarian Notation, but it really should be a team decision. You might find cases where you want to break with the style guidelines.

回答13:

What makes me curious about this question is the fact that the languages (C then C++) where prefixing (i.e., Hungarian notation) was introduced were also strongly-typed. For all I know, it was done with Pascal's use at Microsoft as well. And it would seem that it was also used with Mesa, a strongly-typed language that the Hungarian may have had some familiarity with [;<).

That being the case, it is fair to get beneath the question and consider (1) what problem was prefixing used to help solve and (2) how has that problem gone away?

I know that's not exactly an answer, but it might be more useful than the blanket objections to use of prefixes as outmoded or wrong-headed.

回答14:

Even though the compiler can quickly and easily check the type of a variable, humans are unable to do so while skimming a piece of source code. Therefore some people (like me) prefer to make variable names a tad more verbose, making them quickly recognizable to be global or class variables, string or int, etc.

It might not help the compiler, but when reading a foreign piece of code, it surely saves you having to look up each variable manually...

回答15:

Definitely not. As a general rule, I've come to believe that it's just noise. If you're an indepedent consultant or your company doesn't have a comprehensive style guide, IDesign has a great guide. Just look on the right hand side of the page and you can D/L the latest iteration of their C# Coding Standard document.

Steve

回答16:

I only use it in my database (PostgreSQL)

t_ for table name
v_ for view name
i_ for index name
trig_ for trigger


sp_ for stored procedure name
p_ for parameter    
v_ for variable
c_ for cursor
r_ for record

回答17:

Hungarian notation was never meant to be used to show what data type the variable was. It was misunderstood to suggest that "str" or "i" be used to implicitly define the type. It was meant to only show the "kind" of variable, not the "type."

So to answer the question, it shouldn't be used now nor should it have ever been used in the past.

I know it has been linked, but scroll to the bottom of Joel's article for more info - http://www.joelonsoftware.com/articles/Wrong.html where he talks about where Hungarian

回答18:

For a general overview of good conventions see here: http://msdn.microsoft.com/en-us/library/ms229002.aspx

There is a book about that in which they explain the reasons behind each of that conventions. Pretty interesting read.

回答19:

I always prefix instance member variables with m__ and static member variables with s_. I've come across variable articles from MS people who recommend/discourage the approach.

I'm also pretty sure I've come across the m_ prefix when looking through the standard .NET libraries using Reflector...

回答20:

No, we don't need them. I used to follow this when back in the days, we were forced to follow that kind of a coding standard.

Also with Intellisense, Code Definition Window and Refactoring tools built into VS and other third party plugins like CodeRush express and Refactor Pro, it's easier to work with code without it.

回答21:

Inside the code and when working with data types I see no reason for the use of Hungarian notation.

But when I'm working with a series of user interface control, be that they are textboxes, dropdown lists, grids or what not, I like to have my intellisense work for me. So to accomplish that, I usually make the id of the control with a prefix of "uxSomeControlName". This way, when I'm looking for that textbox to grab it's text value, all I have to do is type "ux" and all of the user interface ID's are displayed. No need to search for txt, ddl, grd, or anything else.

Now is this correct, if you read the above, no. But I don't want to sit hear and try to remember a dozen or more control names when I just have to know two letters.

Like I said, this is only when working on the front end.

回答22:

I use it all the time but that could because I use VBA with Access and Excel.

For me CountAll is a name intCountAll is a name with this difference that it additionially describes the name (never intended for machines just for humans) like sintCountAll tells me its static pintCountAll private and gintCountAll global so for the purpose I use it; it is very usefull.

• control names is a time safer like instead of ControlName I have lblControlName, txtControlName, cboControlName, lstControlName etc so when I use VBA I just type lst and I have all the names I need so I don't have to remember what is the exact name which saves me a lot of time but again this is mainly VBA in Access and Excel.

Regards Emil

回答23:

The only prefix I would consider for C# is a _ for member variables such as

public class Test
{
    private int _id;
}

回答24:

I would say that in most languages these days that have a limited set of types - in particular no concept of unsigned types - then a well-named variable shouldn't need the prefix.

In languages that have signed and unsigned types, or a slew of similar types (e.g. short, int, long or Int8, Int16, In32), then prefixes are useful, despite what anybody else has or will say (and they will, you know it).

The compiler will, at best, give a warning when you try and mix integral types of different signs in expressions, and this could easily be missed if, for example, you configure your IDE to only show errors (not warnings) in a build in the final summary (as you can do with Visual Studio). Mixing signs in arithmetic can seriously ruin your day, so save you or your successor a headache and give them a clue. Remember - you're not the only one who will ever look at the code.

回答25:

A solution to a problem that doesn't exist.

回答26:

While many programmers today are abandoning it, I would still use it in certain cases. Here are some of them;

• If you are maintaining code that already uses it, then I would keep using it.

• When your company style guidelines still require or even suggest it.

• When your documentation has a simple alphanumerically sorted list of variables, it helps group like types.

回答27:

I sometimes use a kind of prefix where pName is a parameter passed into my function (notice I don't prefix the type), oName is local to my current method, mName is a member to the class I'm in and cName is a constant or static readonly member.

Personally I find it helps.

回答28:

The short answer is NO. But...

I see the point of getting away from Hungarian notation, the standards in our shop forbid it, too, but I still find it useful in my one-off or little utility projects for one reason and one reason only: when I am coding to a large number of controls in a web or win form, using HN makes it easy to use Intellisense make sure I catch every single control while coding.

If I have a five checkboxes and their names all start with chk then typing chk gives me the list of every one of them and I can easily pick which one I'm working on that moment.

Also, sometimes I find myself wondering "what the heck was that checkbox named again?" And I have to break off and look in the .ASPX page again.

One way I have compromised is to begin with HN, and then once I have gotten the main code in a win or web form complete, my last step is to do global renames for the HN-named controls. This has actually worked well for me. YMMV, of course.

回答29:

No, if your methods are so long that you cant read the definition at the same time as the use, or the name doesnt imply the type then you have more serious design issues than just naming.

However, i INSIST that you do prefix controls with their type, such as txtName.

来源：https://stackoverflow.com/questions/309205/are-variable-prefixes-hungarian-notation-really-necessary-anymore