checking for eof in string::getline

Question

How do I check for end-of-file using the std::getline function? If I use eof() it won't signal eof until I attempt to read beyond end-of-file.

Answer 1

The canonical reading loop in C++ is:

while (getline(cin, str)) {  }  if (cin.bad()) {     // IO error } else if (!cin.eof()) {     // format error (not possible with getline but possible with operator>>) } else {     // format error (not possible with getline but possible with operator>>)     // or end of file (can't make the difference) } 

Answer 2

Just read and then check that the read operation succeeded:

 std::getline(std::cin, str);  if(!std::cin)  {      std::cout << "failure\n";  } 

Since the failure may be due to a number of causes, you can use the eof member function to see it what happened was actually EOF:

 std::getline(std::cin, str);  if(!std::cin)  {      if(std::cin.eof())          std::cout << "EOF\n";      else          std::cout << "other failure\n";  } 

getline returns the stream so you can write more compactly:

 if(!std::getline(std::cin, str))