Mapping from mapped drive to real share

Suppose I have this folder:

R:\Extensions

But the network share of this folder is
\\computer\somename$\Extensions

How can I get the second value from the first?

You could try looking in the registry, under
HKEY_CURRENT_USER\Network

Nothing in HKCR, HKLM and HKCU.

Code:

TCHAR szUnc[MAX_PATH];

if (NOERROR == WNetGetConnection(TEXT("R:"), szUnc, MAX_PATH))
{
    printf("Unc path of 'R:' is '%s'", szUnc);
}
else
{
    printf("No luck!");
}

WNetGetConnection

That's the one I was looking for.

Thanks