title: use of srand() in c++
body: <p>I am new to c++ so this doubt might look basic but I am not getting the difference between rand() and srand() and what do u mean by "seed" in srand()?
  when I write srand(time(NULL)), what does it do to generate random numbers, what does time(NULL) do here? and what is it?
  Thanks in advance</p>