C++ - can't move istringstream definition out of loop

Question

I have the following piece of code:

#include <sstream>
#include <iostream>
using namespace std;

int main()
{
    string inp, s;
    istringstream iss;
    do
    {
        getline (cin, inp);
        iss(inp);
        int a = 0, b = 0; float c = 0;
        iss >> s >> a >> b >> c;
        cout << s << " " << a << " " << b << " " << c << endl;
    }
    while (s != "exit");
}

which generates the following error:

error: no match for call to ‘(std::istringstream) (std::string&)’

I know that the issue may be averted by using istringstream iss(inp); within the loop, however, is it not possible to move this defintion out of the loop?

(Of course, it is possible to move it out, only that I can't accomplish anything.)

Answer 1

You cannot call an object constructor after the object declaration. Furthermore std::istringstream::operator ()(std::string) is not (usually) declared anywhere.

Use std::istringstream::str(…) to assign its content after construction.