ifstream gcount在getline字符串重载时返回0

Question

I'm finding that gcount on an ifstream object after a call to

  getline(istream &, string &) 

returns 0.

Is this supposed to be the case?

Answer 1

Yes, gcount() is supposed to return the number of characters extracted by the last unformatted input operation performed on the object.

getline() is listed in the functions supposed to updated gcount() , but it is the member getline() of a stream and not the string getline() .

In case of doubt, this link tells it black on white: Behaves as UnformattedInputFunction, except that input.gcount() is not affected.