The C library includes strftime specifically for formatting dates/times. The format you’re asking for seems to correspond to something like this:
char buffer[256];
strftime(buffer, sizeof(buffer), "%a %b %d %H:%M:%S %Y", &your_tm);
I believe std::put_time uses a similar format string, though it does relieve you of having to explicitly deal with a buffer. If you want to write the output to a stream, it’s quite convenient, but to get it into a string it’s not a lot of help — you’d have to do something like:
std::stringstream buffer;
buffer << std::put_time(&your_tm, "%a %b %d %H:%M:%S %Y");
// now the result is in `buffer.str()`.
std::put_time is new with C++11, but C++03 has a time_put facet in a locale that can do the same thing. If memory serves, I did manage to make it work once, but after that decided it wasn’t worth the trouble, and I haven’t done it since.