How do I copy binary data to a stringstream

Question

I have a std::vector<int> and I want serialize it. For this purpose I am trying to use a std::stringstream

 vector<int> v;
 v.resize(10);
 for (int i=0;i<10;i++)
 v[i]=i;


 stringstream ss (stringstream::in | stringstream::out |stringstream::binary);

However when I copy the vector to the stringstream this copy it as character

ostream_iterator<int> it(ss);
copy(v.begin(),v.end(),it);

the value that inserted to buffer(_Strbuf) is "123456789"

I sucssesed to write a workaround solution

for (int i=1;i<10;i++)
   ss.write((char*)&p[i],sizeof(int));

I want to do it something like first way by using std function like copy

thanks Herzl

Answer 1

Actually, this is your workaround but it may be used with std::copy() algorithm.

   template<class T>
   struct serialize
   {
      serialize(const T & i_value) : value(i_value) {}
      T value;
   };

   template<class T>
   ostream& operator <<(ostream &os, const serialize<T> & obj)
   {
      os.write((char*)&obj.value,sizeof(T));
      return os;
   }

Usage

ostream_iterator<serialize<int> > it(ss);
copy(v.begin(),v.end(),it);

Answer 2

I know this is not an answer to your problem, but if you are not limited to the STL you could try (boost serialization) or google protocol buffers

Boost even has build-in support for de-/serializing STL containers (http://www.boost.org/doc/libs/1_45_0/libs/serialization/doc/tutorial.html#stl)