# File:		tr1.pl
# Author:	Jason L. Bryant
# Title:	This program asks for an integer, makes a string of 
#		that many characters with a set alphabet, and  replaces letter a	
#	OUTPUT:
#	Alphabet = a c g t
#	Enter an integer (length of string)? 5
#	Generated String is acgaat
#	Modified String is cgt

@Alpha = ('a','c','g','t');
print "Alphabet = @Alpha\n";
print "Enter an integer (length of string)? ";
$N = <STDIN>;
$i = 0;					# i for while
$str = '';					# initialize final S with empty ''
while ($i < $N ) {
	$i = $i + 1;
	$pos = int rand(4);		# generates random integer < 4
	$str = $str . $Alpha[$pos];		# concatenation with .
}	
print "Generated string is $str\n"; 
$str =~ tr/a/ /;	#replaces all a's with spaces
print "Modified string is $str\n";
exit;