sstream knowledge

[Albo Coder]

Can anyone explain me whta does line 23 do??

  // example about structures
#include <iostream>
#include <string>
#include <sstream>
using namespace std;
struct movies_t {
  string title;
  int year;
} mine, yours;

void printmovie (movies_t movie);

int main ()
{
  string mystr;

  mine.title = "2001 A Space Odyssey";
  mine.year = 1968;
  cout << "Enter title: ";
  getline (cin,yours.title);
  cout << "Enter year: ";
  getline (cin,mystr);
  stringstream(mystr) >> yours.year;
  cout << "My favorite movie is:\n ";
  printmovie (mine);
  cout << "And yours is:\n ";
  printmovie (yours);
  system("pause");
  return 0;
}

void printmovie (movies_t movie)
{
  cout << movie.title;
  cout << " (" << movie.year << ")\n";
} 

[AbstractionAnon]

stringstream treats a string as a stream.
http://www.cplusplus.com/reference/sstream/stringstream/?kw=stringstream

In this case, line 23 constructs a stringstream from mystr, then uses it as an input stream to read from it into yours.year effectively letting the stream do the conversion from the string into an int.

[Albo Coder]

Is there any other way to do this?

[AbstractionAnon]

You could replace lines 22-23 with:

 
  cin >> yours.year;

[Albo Coder]

I guess this is better...
Is there sth that only sstream can do and others cant???

[AbstractionAnon]

Note that the code uses getline at line 20 to input the title rather than cin >>.
This allows the title to contains spaces. cin >> would stop at the first whitespace.

In the case of the year, cin >> could have been used directly.
Also note that the code doesn't do any error checking.
What if a non-numeric is entered for year?

stringstream inherits from istream, so it has all the same conversion functionality as istream.

[Albo Coder]

Nice explanation!!! Thanx!!!

[Albo Coder]

If non-numeric is entered It will say year=0;

[chipp]

you need to filter the user's input, e.g.:

do {
     std::cout << "enter year: ";
     std::cin >> yours.year;
} while (yours.year == 0 /*or something*/);

[Albo Coder]

thanks