Frank Birbacher wrote:

Robert Ramey schrieb:

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The real easy way is just to use a binary_object which saves/loads a specified number of bytes. so the above would look like:

void write_to_cbuffer(char* buf_p, size_t* buf_sz_p) { // note only one * std::ostringstream oss; boost::archive::text_oarchive oa(oss); oa << binary_object(bf_sz_p, mc); } void read_from_cbuffer(const char* buf, const size_t buf_sz) { std::istringstream iss(buf_str); boost::archive::text_iarchive ia(iss); ia >> binary_object(buf_sz, buf) }

You got this one mixed up. The char array is not something to serailize but it is the storage to searialize to. The "read_from_cbuffer" function does *read* the cbuffer and construct a my_class instance out of it by using serialization. The "write_to_cbuffer" serializes a my_class instance an stores the result in the cbuffer.

I can think of using the old strstream class to read from the buffer or take something from Boost.IOStreams. And writing could be faster if you use a std::deque wrapped with IOStreams and later on std::copy this into a char array (instead of memcpy). A deque has usually better performance on push_back than a vector or string, I guess. But then I don't know the internals of a stringstream.

Frank

Frank is right. I don't quite know what Robert thought I was looking for, but it's pretty clear that his suggested code does not do what I want. (Nor does it compile!) To clarify: write_to_cbuffer() should serialize a my_class instance into a c-style char* buffer. It also needs to dynamically allocate storage for the buffer, set buf_p to point at the buffer, and set buf_sz to the size of the buffer. This is so that the legacy C code can then call write(fd, buf_p, buf_sz). read_from_cbuffer() does the opposite: it extracts a serialized instance of my_class from a char* buffer. I'll take a look at the boost::iostreams stuff to see if I can figure out how to make that work. Thanks for the tip, Frank. BTW, I don't think a push_back() is any faster for a deque than a vector -- it is push_front() that is faster for a deque. From the STL docs at SGI: "The main way in which deque differs from vector is that deque also supports constant time insertion and removal of elements at the beginning of the sequence". -- Dominick