Copy vector struct to file using ostream_iterator and copy - c++

Question

I'm currently trying to copy a vector to a new text file after making the necessary changes to the vector. I can build the project fine, but its giving me weird errors that I don't understand. Could anyone possibly help me with this?
My struct
class AccDetails {
public:
string username;
string name;
string topicid;
string testid;
};
The code that is giving me the errors
vector<AccDetails>accInfo;
ofstream temp ("temp.txt");
ostream_iterator<AccDetails>temp_itr(temp,"\n");
copy(accInfo.begin(),accInfo.end(),temp_itr);
There's a whole chunk of error lines, but i think this should be the important 2 lines:

Answer 1

You'll need to overload operator<< for AccDetails. It is what ostream_iterator calls internaly.
Something like this:
std::ostream& operator<<(std::ostream& stream, const AccDetails& obj)
{
// insert objects fields in the stream one by one along with some
// description and formatting:
stream << "User Name: " << obj.username << '\n'
<< "Real Name: " << obj.name << '\n'
<< obj.topicid << ' ' << obj.testid << '\n';
return stream;
}
The operator takes the stream it inserts to as first parameter and a constant reference to the object it is streaming as the second one (this allows passing temporary AccDetails, too). Now you can also say:
AccDetails acc;
std::cout << acc;
If the operator would need access to AccDetail's private fields, you would need to declare as a friend.
If you're new to operator overloading, I suggest you read this SO thread.
Hope that helps.

Answer 2

Can have this after overloading as jrok said:
class AccDetails
{
std::string username;
std::string name;
std::string topicid;
std::string testid;
friend std::ostream& operator<<(std::ostream&, const AccDetails&);
friend std::istream& operator>>(std::istream& is, AccDetails& );
};
std::ostream& operator<<(std::ostream& os, const AccDetails& acc)
{
os << "User Name: " << acc.username << std::endl
<< "Name: " << acc.name << std::endl
<< acc.topicid << ' ' << acc.testid << std::endl;
return os;
}
std::istream& operator>>(std::istream& is, AccDetails& acc)
{
is >> acc.username >>acc.name >> acc.topicid >> acc.testid ;
return is;
}
int main()
{
std::vector<AccDetails>accInfo;
std::copy(std::istream_iterator<AccDetails>(std::cin),
std::istream_iterator<AccDetails>(),std::back_inserter(accInfo) );
std::ofstream temp("temp.txt",std::ios::out);
std::ostream_iterator<AccDetails>temp_itr(temp,"\n");
std::copy(accInfo.begin(),accInfo.end(),temp_itr);
}