My understanding is that a pseudo-random number generator basically just takes some number (the seed), hashes it with a bunch of XORs and bitshifts, and then spits out a really long number from which a remainder can be retrieved to get your "random" number.
Now, usually you'd use time(NULL) as the seed for rand() in C/C++. However, time(NULL) only increments every second, not every millisecond. So how, then, can I for loop over rand() a thousand times in less than one second and still get different numbers as outputs if the seed is still the same time(NULL) value?
rand() uses the previous random value as the new seed on subsequent calls. This is why a unique random sequence of values will be generated when you start with a different seed value.