It means that the person who wrote the code is very old... ;-)

hi,
it usually means that x is a member variable... many naming convensions are
available all over the net... naming member variables with an underscore
prefix is part of one of them...  another one sugget to use "m_" instead of
just "_" so it would give m_x

I hope it helps...

ThunderMusic

To the compiler, no difference at all. It's just another name.

However, we, for example, use the _x convention for member variables.
The biggest advantage is with Intellisense. We used to do this:

private string description = "";

public string Description
{
   get { return this.description; }
   set { this.description = value; }
}

but since Intellisense is case-sensitive, we often had errors in the
code that used the field instead of the property, or vice versa. With
the underscore, there's no ambiguity in Intellisense:

private string _description = "";

public string Description
{
   get { return this._description; }
   set { this._description = value; }
}

The other advantage is that in the debugger, the "_" is sorted before
"a", so all of the fields show up at the beginning of an object's
state, so there's no need to search for them.

Another common use of the _ is to prefix parameters to a method .. often
this is done with m_ prefixing members.

ex:

public class foo {
   print int m_Bar;
   public void DoSomething(int _Bar) {
        m_Bar = _Bar;
   }
}

Another advantage of using _varName besides what Bruce indicated, is that if
you select
private int _varName in your code and choose Refactor in VS 2005, and create
a property, it will recognize the underscore and create all your property
code perfectly with a

public int VarName

propertyName, saving a lot of tedious repetitive, and mind-numbing code -
writing.

Peter