# File:	rand2.pl
# Title: 	Generate a random string of length N (ask for N)over an alphabet 
# Author:	Mihaela Malita
#		Generates a random string over	Alphabet=  A C G T	
#	 	Length of the string? 10
#		0230111100
#		Generated string is AGTACCCCAA
@Alphabet= ('A','C','G','T');		# declare variable array Alphabet
print "Generates a random string over Alphabet= @Alphabet"; 
print "\nLength of the string? ";
$n = <STDIN>; chop($n);
$s = randstring();				#invokes subroutine
print "\nGenerated string is $s"; 
exit;
# use a subroutine $n is global variable
sub randstring {
	my($s) = '';				# initialize final S with empty ''
	$len = @Alphabet;			# length of the Alphabet (4)
	for (1..$n) {				# $n is a global variable
		$die = int rand($len);		# generates random 0 <= integer < L
		print $die;					#ramdom index form Alphabet
		$s = $s . $Alphabet[$die];	# concatenation with .
	}	
return $s;
}