The exception error,didn't catch the connection of null user name,help!

Question

help me !
I use the occi and vc to execute a program,
when i use a NULL database name or use a NULL user name to connect the oracle,the statement "try...catch(SQLException ex)"
didn't catch the error,how i can do?
who can tell me how to change the code,and give me the code of resolved.
the code is:
try
env=Environment::createEnvironment(Environment::DEFAULT);
conn=env->createConnection(m_user,m_pwd,m_dbbase);
}catch(SQLException ex)
when the m_dbbase is NULL or m_user is NULL,the Exception didn't being catched.

Answer 1

#include"iostream.h"
#include <string>
#ifndef occi_ORACLE
#define WIN32COMMON
#include "occi.h"
#pragma comment(lib,"D:\\oracle\\product\\10.1.0\\Db_1\\oci\\lib\\msvc\\vc6\\oraocci10.lib")
using namespace oracle::occi;
using namespace std;
#endif
void main()
     Environment *env;
     Connection * con;
try
env = Environment::createEnvironment(Environment::DEFAULT);
con = env->createConnection("","","");
catch(SQLException excep)
cout<<"Error while connect: "<<excep.getMessage().c_str();
the code is as over,my system is windows2003,the Oracle is 10g,the VC is 6.0,
when I build the program,No error,when go(F5) to the statement "con = env->createConnection("","","");",popup a MessageBox----"Unhandled exception in testt.exe (ORACLINT10.DLL):0xC0000005:Access Ciolation.",the con value is 0xCCCCCCCC,
and another question being found,the statement "cout<<"Error while connect: "<<excep.getMessage().c_str();" be decreased the .c_str();
error C2679: binary '<<' : no operator defined which takes a right-hand operand of type 'class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >' (or there is no acceptable conversion)
how to use the string type?which top file i must add?