Does one need to call srand() C function per thread or per process to seed the randomizer?

Question

The caption pretty much says it.

PS. This is for C++ Windows program.

Answer 1

No, as per the Standard, because once you call srand() it affects rand() calls from all threads.

C library function srand() is single-threaded just like all other functions are, which means if you call srand() from one thread, it affects the number-seqeunce generated from rand() in other threads as well.

But Microsoft provides non-standard srand() which does require you to call it from all threads.