Cin in a while loop

Question

So, I\'ve looked around and haven\'t been able to figure out what\'s going on with cin during my While loop. I\'m working through the book C++ Primer (5th edition) and I noticed

Answer 1

CTRL-D works on Linux. A simpler code snippet is below:

vector vd;
for (double d; cin>> d;)
     vd.push_back(d);
for(int i=0; i