lenti215 [~/perltest]>more rand.pl
#!/usr/bin/perl -w
#

#assign amino acid names and corresponding 1 letter codes to arrays
@aa_names = ('alanine', 'arginine', 'aspartate', 'asparagine', 'cysteine',
'glutamate', 'glutamine', 'glycine', 'histidine', 'isoleucine',
'leucine', 'lysine', 'methionine', 'phenylalanine', 'proline',
'serine', 'threonine', 'tyrosine', 'tryptophan', 'valine');

@aa_1codes = ('A', 'R', 'D', 'N', 'C', 'E', 'Q', 'G', 'H', 'I', 'L', 'K',
'M','F', 'P', 'S', 'T', 'Y', 'W', 'V');

# seed random number generator
srand (15); # use a constant seed this time

# start main program loop
$again = "y";
until ($again ne "y") {

# print random value (aa name) and key (1 letter code)
$code = int (rand (scalar (@aa_names)));
print $aa_names[$code], "  ", $aa_1codes[$code], "\n\n";

# end main program loop
print "Again (y/n)? ";
chomp ($again = <STDIN>);
$again = lc ($again);
$again = substr ($again,0,1);
}

exit;
lenti216 [~/perltest]>perl rand.pl
cysteine  C

Again (y/n)? y
glutamine  Q

Again (y/n)? y
asparagine  N

Again (y/n)? n
lenti217 [~/perltest]>perl rand.pl
cysteine  C

Again (y/n)? y
glutamine  Q

Again (y/n)? y
asparagine  N

Again (y/n)? n
lenti218 [~/perltest]>