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

Question

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.

Incoherent

Duplicate: #112433 – Salomesalomi

Interesting read about the origin of Hungarian notation and why it originally made sense: joelonsoftware.com/articles/Wrong.html – Erasme

Related: #202607 – Honeydew

Answer 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.

Of course, these guidelines are not binding or mandatory outside of Microsoft. However, this is the published recommendation of the platform vendor, and it goes beyond merely removing the positive recommendation from any prior guide, to instead a strongly-worded and emphasized negative recommendation today.

In other words, don't use them anymore.

Immolation

To be fair though, the MS style guidelines are arbitrary for large parts and thus not a useful point of reference. – Selectman

@Konrad, because something is arbitrary doesn't mean they aren't useful. Sometimes simply having a standard in and of itself is useful. Having something consistent is powerful. Hungarian is, arguably, not consistent. Checkbox? cb? cbox? ckb? This is why I fight against it. – Chatterbox

Since when is some guideline-writer in MS the last word? Sure standards are good, but not when they are set in concrete. Just today I was writing iaWhichDose because I wanted something that clearly said it was an integer array of "which dose" indexes, and iCat which clearly says it is the index of a category. The name tells me what it means, without getting really verbose. What on earth is accomplished by disallowing that? – Purchase

@Mike - Where did you get "set in concrete/disallowed" from "[not] really necessary any more/recommend against it"? – Immolation

MS style guidelines "recommend against it"? They say "Do not use Hungarian notation"? Maybe it's just me, but is that a tad dogmatic? – Purchase

@MikeDunlavey In those cases I'd suggest WhichDoseIndexes and CategoryIndex. Abbreviations don't read as well. Plain English longer names are imho better. – Acetous

Answer 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.

Alialia

The _ prefix is really nice for private members if you have to move back and forth between VB and C# a lot, since the convention works well in both places. – Immolation

Reading back my post, I noticed I put 'local variables' where I meant 'class members'... no wonder it got down-voted – Alialia

I agree that the names for controls are one of few places they are ok to use. Anywhere else they should be avoided. – Carranza

Answer 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.

Innocence

I wish I could vote this p twice. The usefulness of this for readability is worth one, plus one for the intellisense trick! – Annisannissa

This is my favorite convention, although I don't distinguish between the input/output parameters. – Ferris

Agree completely: type prefixes: no; scope prefixes: yes. (although I use a different set). It has the additional benefit of avoiding naming conflicts; (ie: a field, parameter, and local can all share the same 'name' without having to get overly creative: var arg = argument; Argument = argument; VS var agument = pArgument; mArgument = pArgument;). – Fleeman

Answer 4

Nope. Did we ever need to?

Savadove

Andrew, joels code is full of prefixes on both variables and table columns. – Incoherent

True. My point was to draw the distinction between "Petzold Hungarian" that the questioner gave examples of and the real thing. – Savadove

+1 for JoelOnSoftware...he's a genius – Radiolucent

Answer 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"

Misdate

Answer 6

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

Lannielanning

Answer 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.

Diphthongize

IMHO, Java would be a vastly better language if Hungarian notation were used as it was originally meant. If a field has type int[], it will often be very important to know whether whether other references may exist to that same array, and whether the contents of that array may ever change. Nothing in Java's type system says anything about either of those things, but including such information within names could make a many kinds of of mistakes much more obvious. – Monticule

Answer 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.

Croissant

Answer 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.

Blastema

Answer 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.

Catch

Answer 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.

Bloodyminded

Answer 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.

Bur

I am all for collaborative team decisions, but I cannot agree that the team should choose to use outdated standards for comfort. Honestly, it does not foster development of skills to do things a certain way because it "has always been done like that". Just adding a counter to your counter. :-) – Bloodyminded

I agree with your counter, and raise you this counter. You shouldn't change just for change's sake either. There may be a very important reason those are named a certain way. So figure out that reason, and either stick to it, or rename them. Just make it a team decision. :) – Bur

Answer 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.

Headsail

What's even more ironic is that I've never seen Hungarian notation used in the spot where I'd consider it most important: distinguishing whether a field of a mutable reference type (e.g. int[]) holds the only reference to a safely-mutable object, or a possibly-shared reference to an object that--even though it's of a mutable type--must never be mutated. The distinction is extremely important, and IMHO Java and C# would be better languages if they encouraged the use of Hungarian notation to distinguish between the different "kinds" of references. – Monticule

Answer 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...

Diametral

Only if you're reading the code outside of the IDE. If it's in the IDE, all the information is available just by hovering the mouse over the variable. – Immolation

That assumes a lot about the IDE the other reader of the code has available and chooses to use. I do not assume an IDE in my code, and I very much favor the attitude that Frans-WIllem offers here. – Headsail

Answer 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

Theoretician

Answer 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

Hf

Answer 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

Oppose

Answer 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.

Strongwilled

Answer 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...

Glennieglennis

Somebody hates prefixing local member variables, that's for sure :) – Alialia

+1 from me... but I use the convention without an underscore... and g for variables in the global namespace. (This is in C++) – Veracity

Answer 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.

Grapnel

Answer 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.

Overtake

Answer 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

Tigges

Answer 23

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

public class Test
{
    private int _id;
}

Imposing

Is that part of the standard style? – Noctambulous

Yes, it is. The MS standard for private member variables (at least in C#, not sure about VB.NET) is to prefix them with underscore. This is useful with the Refactoring tool in Visual Studio. You can right-click on the underscore-prefixed member variable, select Encapsulate, and it will generate the member variable's corresponding property, including getter and setter. Just like this: private int _id; would generate: public int Id { get { return _id; } set { _id = value; } } Sweet! – Entomophagous

Answer 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.

Zeal

Answer 25

A solution to a problem that doesn't exist.

Angarsk

Answer 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.

Pierrette

Answer 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.

Khabarovsk

Any modern IDE will give you that information – Thumbsdown

Answer 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.

Entomophagous

Answer 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.

Derangement

Prefixes on controls drive me nuts. – Lundin