calling SQLDriverConnect with ";" in password fails, same with ODBC works

Hi,
on a windows 2008 machine that has the Oracle instant client 11_1 installed (11.01.00.06) i am calling SQLDriverConnect in the following way:

std::string str = "Driver={Oracle in instantclient11_1};Dbq=//10.10.101.66:1521/orcl;;Uid=myUser;pwd=a;b";
odbcRc = SQLDriverConnect(hdbc, NULL, (SQLTCHAR*)str.c_str(), str.size(), (SQLTCHAR*)szConnStrOut, 1024, &cbConnStrOut, SQL_DRIVER_NOPROMPT)) == SQL_ERROR);

as long as the password contains no special chars (namely semicolon) it works fine. but when I try to use special chars in the password It stops working, with an invalid username/password error.
State: 28000 Native error: 1017 Message: [Oracle][ODBC][Ora]ORA-01017: invalid username/password; logon denied

i tried different variations of adding " (\") over the password, over the entire pwd=a;b or braces { but nothing seems to work.
the thing is that using ODBC works! what I did was:

open ODBC, go to System DSN tab, add "Oracle in instantclient11_1", then fill the following information:

Data source name: Anything
TNS Service Name: //10.10.101.66:1521/orcl
User ID: myUser

then i press test connection, enter the password "a;b"
and it works!

I cannot figure out what's my problem.

Thanks,
Roy.