Question

How does the value produced by rand function depends on it seed value.When we do not define any seed then how does its values differ.
Below is a code that i found for generating numbers for an integer array can any one please explain :

#!/usr/bin/perl -w

  # Linear search of an array

  # Note that if you later on want to search for something from a
  # list of values, you shouldn’t have used an array in the first
  # place.

  # Generating 10 integers
  $NUM = 10;
  $MAXINT = 100; # 1 + the maximum integer generated

  srand(); # initialize the randomize seed

  print "Numbers Generated:\n(";
  for $i (1 .. $NUM) {
  push @array, sprintf("%d", rand(1) * $MAXINT);
  print $array[$i-1];
  print ", " unless ($i == $NUM);
  }
  print ")\n\n";

Answer 1

As far as I know perl uses the pseudo-random number generation functions of the standard C library.
It may depend on the implementation but it usually is a Linear Congruential Generator. This kind of PRNG uses its previous value to generate the next, therefore it will need a start value aka the seed.