how do i open and also write to a different directory?

Trying to open a a new file in binary mode in plain C++ on unix and then putting stuff and closing it. I would like to specify a path to open and store the filename . How do i do it? Here's the sample code. I also have to rename it after closing it.


const char *output_file ;

void  create_filename(int &Count, string &outFilename, struct tm *Billing_Time);


create_filename(file_seq, tempFilename, &billing_time);

output_file = tempFilename.c_str();

   ofstream myOutputFile(output_file, ios::binary);
      if ( myOutputFile.fail() ) {
         #ifdef DEBUG
          cerr << "Could not open file for output: " <<              output_file << endl ;
          cerr << "Aborting ." << endl ;
         #endif
         exit(0) ;
      }
//do stuff
.
.
.
myOutputFile.close();
string oldFile = tempFilename;
string renamedFile = tempFilename.replace(2,1,1,'U');

if(rename(oldFile.c_str(), renamedFile.c_str())!= 0) {
 
  cout<<"couldnt rename file \n";
}