ostringstream gives me Implicit instantiation error

Question

I'm trying the elegant solution provided in this answer but no matter what I try, I cannot get passed the error Implicit instantiation of undefined template for this line:

std::ostringstream strs;

What I need to do? I've included the following, which I'm sure is overkill. As a second question it seems hard to track down what exactly needs to be included for ostringstream:

#include <iostream>
#include <fstream>
#include <iosfwd>
#include <ios>

Solution

stringstream classes are defined in sstream header, so write

#include <sstream>

and all will be fine.

Comments

[stardust]

I see the link you have provided and if your intention is to change a double to string and you have C++11 support, just use std::to_string(double).

[johnbakers]

thanks, it worked, I'm curious how I could find this out easily myself. I looked it up and it doesn't say anything about this particular header: cplusplus.com/reference/sstream/ostringstream. My compiler (Xcode) says it is declared in iosfwd

[indeterminately sequenced]

@SebbyJohanns <iosfwd> only provides forward declarations for i/o classes. You need to #include the correct header in your cpp file for the definition. <iosfwd> is present for use in headers where you do not need the full class definition. This helps in reducing compilation times.

[johnbakers]

thanks. i'd still like to know the best way to actually find out what headers include the full definitions of things like this. i was on quite a goose chase to track it down before posing here, and it seems like it should be an elementary task to look up. where would I do that? @indeterminatelysequenced

[indeterminately sequenced]

@SebbyJohanns msdn is the most reliable source I have found online. (other than the standard drafts).

[john]

@SebbyJohanns I think one clue is in the URL of the link you posted. Another is that on that page <sstream> is highlighted in the top left menu.

[Christian Rau]

@SebbyJohanns Use a better reference.

[Christian Rau]

@indeterminatelysequenced "msdn is the most reliable source I have found online" - I wouldn't trust them so much regarding information about the C++ standard either (they made errors and inaccuracies before, though not neccessarily in this case). cppreference.com is still the most reliable source, even if still incomplete in certain parts.