Is ofstream thread safe?

Question

I am working on a program, which uses multiple std::ifstreams for reading a binary file, one std::ifstream for each thread. Now I need to know, if

Answer 1

If I haven't misunderstood you - no, nothing in the standard library is thread safe (except the std::thread specific things, of course (from C++11 and later)). You need additional synchronization.

Even more - if there are several processes, reading from/writing to these files, you need to lock the files, to sync the access.