C++: vector to stringstream

Question

I want to know if it is possible to transform a std::vector to a std::stringstream using generic programming and how can one accomplish such a thing?

Solution 1

Adapting Brian Neal's comment, the following will only work if the << operator is defined for the object in the std::vector (in this example, std::string).

#include <iostream>
#include <sstream>
#include <vector>
#include <string>
#include <iterator>

 // Dummy std::vector of strings
 std::vector<std::string> sentence;
 sentence.push_back("aa");
 sentence.push_back("ab");

 // Required std::stringstream object
 std::stringstream ss;

 // Populate
 std::copy(sentence.begin(), sentence.end(),std::ostream_iterator<std::string>(ss,"\n"));

 // Display
 std::cout<<ss.str()<<std::endl;

Solution 2

If the vector's element type supports operator<<, something like the following may be an option:

std::vector<Foo> v = ...;
std::ostringstream s;
std::copy(v.begin(), v.end(), std::ostream_iterator<Foo>(s));

Comments

[Skurmedel]

+1 only crux is that copy and ostream_iterator should be qualified with std. :)

[Robben_Ford_Fan_boy]

Would you not give the benefit of the doubt that using namespace std was at the start of the method?!!! :)

[Harsh Pathak]

Lol, might as well be consistent :)

[Edward Strange]

No no no! It must transform the vector!

[Harsh Pathak]

@Noah: Lol, do you propose a change of basis or a magic potion :) ?

[Dai Doan]

This fails when the vector's element type has no operator<<. I think the OP needs to specify the problem more.

[Skurmedel]

@David Relihan: I'm sure there were, but it could be confusing. :)