lenti220 [~/perltest]>more rand2.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 ; # equivalent to srand (time) - a different seed each time

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

# print random name and 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;

lenti221 [~/perltest]>perl rand2.pl
lysine  K

Again (y/n)? y
methionine  M

Again (y/n)? y
arginine  R

Again (y/n)? n
lenti222 [~/perltest]>perl rand2.pl
threonine  T

Again (y/n)? y
threonine  T

Again (y/n)? y
tryptophan  W

Again (y/n)? n
lenti223 [~/perltest]>