creating filenames dynamically

I've been doing a screenshot program, and thus far have hardcoded my filename and path.

CFbsBitmap* iBitmap;
iBitmap = new (ELeave) CFbsBitmap();
TInt err = iBitmap->Create(TSize(352,416),EColor64K);
CEikonEnv::Static()->ScreenDevice()->CopyScreenToBitmap(iBitmap);
iBitmap->Save(_L("C:\\Nokia\\Images\\test.mbm"));

The problem with this is that if I want to create several screenshots, they will all overwrite the original "test.mbm".  I want to make it so it will start out at "test001.mbm", then the next screenshot will go to "test002.mbm" etc.  Is there any way to do this by parsing the filenames of the existing files in the directory?

Thanks,
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