rand, srand - random number generator
unsigned int seed;
The newer random(3) should be used in new applications; rand
remains for compatibility.
Rand uses a multiplicative
congruential random number generator
with period 2**32 to return successive pseudo-random numbers in the
range from 0 to (2**31)-1
The generator is reinitialized
by calling srand with 1 as argument.
It can be set to a random starting point by calling srand with
whatever you like as argument.