c++ how to partially add a chararray to vector

what is the best way to do code below:

vector<char> content;
char MESSAGE[1024];
SUCCESSFUL = recv(sock_CONNECTION, MESSAGE, 1024, NULL);
for (int i = 0; i < SUCCESSFUL; i++)
    content.push_back(MESSAGE[i]);

i just found something like:

content.get_allocator = MESSAGE; 

has no error, but i don't know how to cut MESSAGE array from 0 to SUCCESSFUL!