Extracting from istream into stringstream

[Ney André de Mello Zunino]

Hello.

Is g++ 3.3.3 (Cygwin) correct in rejecting the following test program?

#include <istream>
#include <sstream>
#include <fstream>

void test(std::istream& source)
{
std::stringstream ss;
source >> ss; // offending line
}

int main()
{
std::ifstream source("simples.pgm");
test(source);
}

The compiler complains about an ambiguous overload on the line where the
program tries to extract elements from the istream and into the
stringstream. Shouldn't that be a valid operation? Or, what might I be
missing?

Thank you,

--
Ney André de Mello Zunino

[Victor Bazarov]

Ney André de Mello Zunino wrote:

Is g++ 3.3.3 (Cygwin) correct in rejecting the following test program?

#include <istream>
#include <sstream>
#include <fstream>

void test(std::istream& source)
{
std::stringstream ss;
source >> ss; // offending line
}

int main()
{
std::ifstream source("simples.pgm");
test(source);
}

The compiler complains about an ambiguous overload on the line where the
program tries to extract elements from the istream and into the
stringstream. Shouldn't that be a valid operation? Or, what might I be
missing?

std::stream is never used like

std::stream s ...
blahblah >> s;

but always

std::stream s ...
s << blahblah;

So, your attempt is a bit misguided, I believe. You might want to do

while (source) {
char c;
source >> c;
ss << c;
}

or use 'get' and 'put' if you want to speed it up, something like

while (source)
ss.put(source.get());

Victor

[Ney André de Mello Zunino]

Victor Bazarov wrote:

So, your attempt is a bit misguided, I believe. You might want to do

It was indeed. I realized it some time after posting the message and
even cancelled it. But you were too quick! :)

Anyway, it is almost 3:00am here and I should give my neurons a rest.

Thanks for your response, though.

--
Ney André de Mello Zunino