Question

#include <iostream>
#include <sstream>

using namespace std;

int get_4()
{
  char c = '4';
  stringstream s(ios::in);
  s << c;
  int i;
  s >> i;
  return i;
}

int main()
{
  cout << get_4() << endl;
}

The conversion is not working for me. If I write a character ‘4’ or character array {‘4′,’\0’} to stringstream and then read it out to int i, I don’t get back the 4. What is wrong with the above code?

Answer 1

Because you set the stringstream to input-only — no output.

If you check the fail() bit after trying to extract the int, you’ll see it didn’t work:

 s >> i;
  bool b = s.fail();
  if( b )
      cerr << "WHOA DOGGIE!  WE BLOWED UP\n";

---

In your code, change:

stringstream s(ios::in);

to:

stringstream s;