The following program compiles but gets the runtime error:
ORA-12154: TNS:could not resolve the connect identifier specified

I am using Windows 7 and Microsoft compiler cl.exe of Visutal Studio 2010.

Please help. 

// Program name: p1.cpp
#include <iostream>
#include <occi.h>
using namespace std;
using namespace oracle::occi;
int main()
{
    const string user = "HR"; 
    const string pass = "HR"; 
    const string osid = "XE";

    Environment* const env = 
        Environment::createEnvironment(Environment::DEFAULT);
    int ret = 0;
    try
    {
        Connection* const con = 
            env->createConnection(user, pass, osid);
        cout << "Connected!" << endl;
        env->terminateConnection(con);
    }
    catch(SQLException &e)
    {
        cout<<e.what();
    }
    return ret;
}

-----------------------------------------------------------------------
Microsoft compiler command line:
cl.exe /EHsc p1.cpp oraocci10.lib

-----------------------------------------------------------------------
C:\oraclexe\app\oracle\product\10.2.0\server\NETWORK\ADMIN\tnsnames.ora
XE =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = VOSTRO-1510)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = XE)
    )
  )

EXTPROC_CONNECTION_DATA =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC_FOR_XE))
    )
    (CONNECT_DATA =
      (SID = PLSExtProc)
      (PRESENTATION = RO)
    )
  )

ORACLR_CONNECTION_DATA = 
  (DESCRIPTION = 
    (ADDRESS_LIST = 
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC_FOR_XE)) 
    ) 
    (CONNECT_DATA = 
      (SID = CLRExtProc) 
      (PRESENTATION = RO) 
    ) 
  ) 
-----------------------------------------------------------------------
C:\oraclexe\app\oracle\product\10.2.0\server\NETWORK\ADMIN\listener.ora
SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (SID_NAME = PLSExtProc)
      (ORACLE_HOME = C:\oraclexe\app\oracle\product\10.2.0\server)
      (PROGRAM = extproc)
    )
    (SID_DESC =
      (SID_NAME = CLRExtProc)
      (ORACLE_HOME = C:\oraclexe\app\oracle\product\10.2.0\server)
      (PROGRAM = extproc)
    )
  )

LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC_FOR_XE))
      (ADDRESS = (PROTOCOL = TCP)(HOST = VOSTRO-1510)(PORT = 1521))
    )
  )

DEFAULT_SERVICE_LISTENER = (XE)
--------------------------------------------------------------------------
Environment variables:
ORACLE_HOME=ORACLE_HOME=C:/oraclexe/app/oracle/product/10.2.0/server