在 C++ 中询问用户输出文件名

Question

cout << "What name would you like fo you output file?\n";
getline(cin, file);

outfile.open(file.c_str());   

This works fine but I need save my file be save as .txt format

Answer 1

string ext = ".txt"; //file extension

cout << "What name would you like for your output file?\n";
getline(cin, file);
//highly recommend checking user input (for extensions, invalid symbols etc..)
file += ext; //appends ext to file  

outfile.open(file.c_str());

see http://www.cplusplus.com/reference/string/string/ for other operations allowed on std::string