C++ Using open on a string instead of char*

I am using ifstream to open a file using

std::fstream::open
void open ( const char * filename, ios_base::openmode mode = ios_base::in );

However I want to use a string instead of a char* as follows but having a problem on how to do this

string val_ifmodl = �fred.modl�
ifstream  ifs_modl;
ifs_modl.open(val_ifmodl);
 

---------- Post updated at 12:36 PM ---------- Previous update was at 12:02 PM ----------

DONE, I can pass the string using .c_str()

The nicer string types, like Rorguewave RWCString, have an operation overload to cast to char*.

Use:

ifs_modl.open(val_ifmodl.c_str());