Thread: Open last used file

I want to open the last used file i have my prog save the name of it in a text file and then read the name of it but it wont open it.Please could someone ave a look and tell me whats the matter:

Code:

ifstream a_file("D:\\Text LOG\\Txt_log.txt");
                  getline(cin,txt);
                  a_file.close();
                  ifstream b_file(txt.c_str(),ios::app);
                  getline(b_file,txtt);
                  cout<< txtt;
                  cout<<setfill('-')<<setw(80)<<("-")<<endl;
                  cout<<"Please enter some text to be output to this file: ";
                  getline(cin,x);
                  b_file>> x;
                  cin.get();
                  system ("cls");
                  break;