what is the difference in declaring this way

[cmrhema]

Hi,
I have seen many times when variable are declared as
int _qty;

instead of plain
int qty;

Is there any coding preference or rules or any advantage in declaring this way i.e. using _ symbol

Regards
cmrhema

[Sl1ver]

variable has to 1 word

[tlhintoq]

I think most people just use the underscore to indicate the non-public reference of a value.

private int _score = 5; // gives a default value
public int Score
{
     get { return _score;}
     set { _score = value;}
}

Its kind of like prefacing variable names with a letter to indicate their type:

int nScore;
bool bEnabled;
string szName;

[artov]

For coding preferences, you might like to try Microsoft's StyleCop and FxCop.

StyleCop recommends to drop the underlines, btw,

[tlhintoq]

@artov
Interesting. I have a long flight. This will give me something interesting to check out. Thanks!

[r035198x]

There may be rare circumstances when you need to edit code (say add a value in the session) and want to guarantee that the variable name you choose does not clash (and thus hide) an already existing variable name.
Such circumstances are rare and generally you will want to stay away from such evil nomenclature.