safe reading from a stream in a for loop using getline

Answer 1

The iostreams by default do not throw exceptions when errors occur. If you want to enable them:

cout.execeptions( std::ios::badbit );

would enable exceptions if badbit is set.

To enable them all:

cout.execeptions( std::ios::badbit 
                   | std::ios::eofbit 
                   | std::ios::failbit );

The exceptions thrown are of type:

std::ios_base::failure

which is derived from std::exception.

In general though, it is easier not to use execptions, but to use constructs like:

while( std::getline( myStreamObj, line ) ) {
   // process line
}

Answer 2

If you want to capture the errors via exceptions you need to set it using ios::exception. Otherwise an exception will not be thrown. You can check out the documentation here: http://www.cplusplus.com/reference/iostream/ios/exceptions/.

You can also explicitly call ios::fail(), ios::bad() or ios::eof(). Docs here: http://www.cplusplus.com/reference/iostream/ios/