lenti264 [~/perltest]>more arrays2.pl
#!/user/bin/perl -w
# arrays (lists of scalars)
# array names start with @
# define arrays by listing their contents in parentheses,
# separated by commas
# to retrieve the elements of an array, $array_name[element_index]
# the element index numbers start with 0
#
@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');

@aa_3codes = ("Ala", "Arg", "Asp", "Asn", "Cys", "Glu", "Gln", "Gly",
"His", "Ile", "Leu", "Lys", "Met", "Phe", "Pro", "Ser", "Thr", "Tyr",
"Trp", "Val");


print "Enter the single letter code for an amino acid: ";
chomp ($code=<STDIN>);

for $i (0 .. 19)  {

if ($code eq $aa_1codes [$i])  {
print $aa_names [$i], "  ", $aa_3codes [$i], "  ", $aa_1codes [$i], "\n";
                               }
                  }
exit;
lenti265 [~/perltest]>perl arrays2.pl
Enter the single letter code for an amino acid: a
lenti266 [~/perltest]>perl arrays2.pl
Enter the single letter code for an amino acid: B
lenti267 [~/perltest]>perl arrays2.pl
Enter the single letter code for an amino acid: C
cysteine  Cys  C
Enter the single letter code for an amino acid: Arg
lenti268 [~/perltest]>perl arrays2.pl