Iterating through a string with sstream

Question

Here is a piece of code:

#include <sstream>
#include <iostream>

using namespace std;

int main()
{
  stringstream ss;
  string st = "2,3,55,33,1124,34";
  int a;
  char ch;
  ss.str(st);
  while(ss >> a)
  {
    cout << a << endl;
    ss >> ch;
  }
  return 0;
}

It produces the output:

2
3
55
33
1124
34

But if I remove the line ss >> ch it produces the output: 2.

Why does it stop iterating through the string? And what difference does ss >> ch make?

Answer 1

What difference does ss >> ch make?

ss >> ch takes a character from your stream an store it in your char ch variable.

So here it removes each and every comma (,) from your string.

---

Why does it stop iterating through the string without ss >> ch?

Without this operation, your iteration stops because ss >> a fails, since it tries to store a comma inside a, an int variable.

---

Note: If you replace your commas with spaces, you could get rid of ss >> ch, since a space is recognized as a separator.

Example:

#include <sstream>
#include <iostream>

using namespace std;

int main()
{
  stringstream ss;
  string st = "2 3 55 33 1124 34";
  int a;
  ss.str(st);
  while (ss >> a)
    cout << a << endl;
  return 0;
}