stringstream used to convert int to string does work only once?

[Field]

Hi,

the following snippet shows once executed this output:
2
2

I'd have rather expected this output:
2
10

Does anyone know why?

thx4hints,

FF

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

int main(void)
{
string apName;
stringstream ss;

ss << 2;
ss >> apName;
cout << apName << endl;
ss << "10";
ss >> apName;
cout << apName << endl;
return 0;
}

 

[Victor Bazarov]

the following snippet shows once executed this output:
2
2

I'd have rather expected this output:
2
10

Does anyone know why?

Sure. See below.

thx4hints,

FF

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

int main(void)
{
string apName;
stringstream ss;

ss << 2;
ss >> apName;
cout << apName << endl;
ss << "10";
ss >> apName;
cout << apName << endl;
return 0;
}

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

int main(void)
{
string apName;
stringstream ss;

ss << 2;
ss >> apName;
cout << apName << endl;
ss << "10";
if (ss >> apName)
cout << apName << endl;
else
cout << "Could not convert\n";
return 0;
}


V

 

[Steven T. Hatton]

Hi,

the following snippet shows once executed this output:
2
2

I'd have rather expected this output:
2
10

Does anyone know why?

I don't believe the problem is related to converting an int to a string. It
seems to be related to the state of stringstream after the first input and
output. I'm not sure exactly what state it's put into, but if the state is
reset, the second sequence of calls will work as expected. I'll play
around a bit more to see if I can't find a way to determine the exact state
the stringstream is in after the first sequence of calls.

 

[Field]

Thing is, you need to clear the state using clear():

ss.clear(stringstream::goodbit);

before the next call.

Found solution on this site:
http://www.programmingforums.org/forum/showthread.php?t=4224

Thanks to everyone bothering.
Needed to ask here to find the answer elsewhere. As usual..

Little fix: instead of
ss << "10";
I meant:
ss << 10;

obviously..

kr,

FF