binary - C++ memset - Extract size bytes and copy them to the supplied data address from buffer -

is there way set start position char pointer, file in memory.

i need read extract size bytes of data stream, , copy them supplied data address , return number of bytes read. memset tryout, try someting fread file in memory. hope can me.

typedef signed   long long int64; // osx example  int64 filestream::read(void* data, int64 size) {   // make sure, size not > filename   int64 wanted_buffer = currentposition + size;   if (wanted_buffer > memfile->getsize())     size = memfile->getsize() - currentposition;    // tryout memcpy   memcpy(data, currentposition + memfile->getbuffer(), size);   currentposition += size;        //   // return std::fread(data, 1, static_cast<std::size_t>(size), m_file);    return currentposition; } 

if you're able use c file struct can use fseek on file *.