Good Examples of Hungarian Notation? [closed]

Answer 1

The now classic article, as mentioned in other Hungarian posts, is the one from Joel's site:

http://www.joelonsoftware.com/articles/Wrong.html

Answer 2

There's no such thing as a good example of hungarian notation. Just don't use it. Not even if you are using a weakly typed language. You'll live happier.

But if you really need some reason not to use it, this is my favourite one, extracted from this great link:

One followon trick in the Hungarian notation is "change the type of a variable but leave the variable name unchanged". This is almost invariably done in windows apps with the migration from Win16 :- WndProc(HWND hW, WORD wMsg, WORD wParam, LONG lParam) to Win32 WndProc(HWND hW, UINT wMsg, WPARAM wParam, LPARAM lParam) where the w values hint that they are words, but they really refer to longs. The real value of this approach comes clear with the Win64 migration, when the parameters will be 64 bits wide, but the old "w" and "l" prefixes will remain forever.

Answer 3

Do not use language specific prefixes.

We use:

n: Number 
p: Percentage 1=100% (for interest rates etc)
c: Currency
s: String
d: date
e: enumeration
o: object (Customer oCustomer=new Customer();)
...

We use the same system for all languages:

SQL
C
C#
Javascript
VB6
VB.net
...

It is a life saver.

Answer 4

I find that the only helpful point is when declaring interface controls, txtUsername, txtPassword, ddlBirthMonth. It isn't perfect, but it helps on large forms/projects.

I don't use it for variables or other items, just controls.

Answer 5

It's pointless to use Hungarian to indicate types because the compiler already does it for you.

Where Hungarian is useful is to distinguish between logically different sorts of variables that have the same raw type. For example, if you are using ints to represent coordinates, you could prefix x coordinates with x, y coordinates with y and distances with d. So you would have code that looks like

dxHighlight = xStart - xEnd

yHighlight = yLocation + 3

yEnd = yStart + dyHeight

dyCode = dyField * 2

and so on. It's useful because you can spot errors at a glance: If you add a dy to a y, you always get a y. If you subtract two x's you always get a dx. If you multiply a dy by a scalar, you always get a dy. And so on. If you see a line like

yTop = dyText + xButton

you know at a glance that it is wrong because adding a dy and a x does not make sense. The compiler could not catch this for you because as far as it can tell, you are adding an int to an int which is fine.

Answer 6

I think the key thing to take away from Joel's article, linked above, and Hungarian Notation in general, is to use it when there's something non-obvious about the variable.

One example, from the article, is encoded vs non encoded strings, it's not that you should use hungarian 'us' for unsafe strings and 's' for safe strings, it's that you should have some identifier to indicate that a string is either safe or not. If it becomes standard, it becomes easy to see when the standard is being broken.