c++ - How to treat a std::vector like a C buffer efficiently? -

with c buffer, this:

byte buffer[max_size]; int datasize = 0;  while (apprunning())  {     datasize += receive(buffer + datasize, max_size - datasize);      int processedsize = processbuffer(buffer, datasize);     assert(processedsize <= datasize);     datasize -= processedsize;     memmove(buffer, buffer + processedsize, datasize); }; 

is possible std::vector without losing performance?

edit: have found way replace raw c buffer std::vector.

std::vector<byte> vbuf; vbuf.reserve(max_size); // allocated @ once  while (apprunning())  {     int pendingsize = getpendingdatasize(); // socket     if (pendingsize > vbuf.capacity())         pendingsize = vbuf.capacity();      vbuf.resize(pendingsize);     int recvsize = receive(vbuf.data(), vbuf.size());     assert(recvsize < vbuf.size());     int processedsize = processbuffer(vbuf.data(), vbuf.size());     std::rotate(vbuf.begin(), vbuf.begin() + processedsize, vbuf.end());     vbuf.resize(vbuf.size() - processedsize); }; 

actually, in practical usage, receiving data , processing data may done in multithread. using vector, not need manage buffer's allocation, data size , buffer capacity manually. compares c buffer, performance penalty here @ vbuf.resize() calls. think penalty insignificant. better way appreciated.

if want behavior similar c (that is, want guarantee vector won't ever free or allocate more memory underlying vector), nice solution use boost's static_vector. statically allocates underlying buffer otherwise acts normal vector.

boost::static_vector<byte, max_size> buffer; 

for type of activity, however, might std::queue or boost::cirular_buffer , see if 1 of fits needs.