I have this code in my C# class.
#if DEBUG
private const string BASE_URL = \"http://www.a.com/\";
#else
private const string BASE_URL = \"h
That is a "compiler directive", which means it will actually include or exclude the code from the build process (or compiling) based on the #if's that you put in. That being said, the DEBUG symbol is in the properties of your project, and in Visual Studio is generally removed automatically on the "Release" build.
So basically, it doesn't have to be in Visual studio running in debug, and it does not have to be in any certain folder, your code is just built that way.