Ruby, 364 360 - 8 = 352

Still has lots of room for improvement. 99 bottles code stolen from here.

p=gets.upcase
if p=~/[^HQ9+
]/
puts"Source code contains invalid characters"else
p.each_char{|x|case x
when ?H
puts"Hello, world!"
when ?Q
puts p
when ?9
def c;"#{$n} bottle#{'s'if$n>1} of beer on the wall"end
($n=99).times{puts"#{c}, #{c[0..-13]}.
#{$n<2?"Go to the store and buy some more":"Take one down and pass it around"}, #{$n=($n-2)%99+1;c}.

"}end}end

Ruby, 364 360 - 8 = 352

Still has lots of room for improvement. 99 bottles code stolen from here.

p=gets.upcase
if p=~/[^HQ9+
]/
puts"Source code contains invalid characters"else
p.each_char{|x|case x
when ?H
puts"Hello, world!"
when ?Q
puts p
when ?9
def c;"#{$n} bottle#{'s'if$n>1} of beer on the wall"end
($n=99).times{puts"#{c}, #{c[0..-13]}.
#{$n<2?"Go to the store and buy some more":"Take one down and pass it around"}, #{$n=($n-2)%99+1;c}.

"}end}end

Ruby, 364 - 8 = 356

Still has lots of room for improvement. 99 bottles code stolen from here.

p=gets.chop.upcase
if p=~/[^HQ9+]/
puts"Source code contains invalid characters"else
p.each_char{|x|case x
when ?H
puts"Hello, world!"
when ?Q
puts p
when ?9
def c;"#{$n} bottle#{'s'if$n>1} of beer on the wall"end
($n=99).times{puts"#{c}, #{c[0..-13]}.
#{$n<2?"Go to the store and buy some more":"Take one down and pass it around"}, #{$n=($n-2)%99+1;c}.

"}end}end

Ruby, 364 360 - 8 = 352

Still has lots of room for improvement. 99 bottles code stolen from here.

p=gets.upcase
if p=~/[^HQ9+
]/
puts"Source code contains invalid characters"else
p.each_char{|x|case x
when ?H
puts"Hello, world!"
when ?Q
puts p
when ?9
def c;"#{$n} bottle#{'s'if$n>1} of beer on the wall"end
($n=99).times{puts"#{c}, #{c[0..-13]}.
#{$n<2?"Go to the store and buy some more":"Take one down and pass it around"}, #{$n=($n-2)%99+1;c}.

"}end}end