From: Dave Burt <dave@...>
Date: 2006-03-31T07:53:44+09:00
Subject: Re: Learn to Program, by Chris Pine

Jan K wrote:
> It is indented. Must be your client.

Wow, my client's not displaying tabs. That really kinda sucks. Thanks for 
the heads-up!

> The problem was that I didn't realize that I messed up the first
> Grandma program (which reinforced some misconceptions because the
> program was working ok). Then I sort of got this idea that I had to
> use a loop inside a loop and really couldn't get out of that box.
>
> Everything is obvious now.
>
> Agony of defeat, ecstacy of success.

Yay!

Once you've got Flow Control, now you can write programs to do real-life 
useful tasks!

> Anyway, here's the final program:
>
> (hopefully I don't have any superfluous code this time around)

That might be a little much to expect this early in the game :-)

> -----------------------------------------------------------------
> number = rand(21)
> number2 = 0
> keep_count = 0
>
> while keep_count != 3
>  input = gets.chomp
>   if input != 'BYE'
>    keep_count = 0
>    puts 'HUH?! SPEAK UP, SONNY!'
>   else
>    number2 = (keep_count + 1)
>    keep_count = number2
>     if keep_count != 3
>      puts 'HUH?! SPEAK UP, SONNY!'
>     end
>   end
> end
>
> puts 'NO, NOT SINCE ' + (1930 + number).to_s + '!'
> -----------------------------------------------------------------

The line is "number2 = 0" is superfluous, because the first thing you do is 
assign to it, but it does serve to make it obvious to the programmer the 
variable exists.

If it was my program, though, I'd drop the variables "number" and "number2", 
and just use the formula directly place - they're only used once each. Like 
this:
    keep_count = keep_count + 1
And like this:
    puts 'NO, NOT SINCE ' + (1930 + rand(21)).to_s + '!'

Note you don't need parentheses around the formula on the right-hand side of 
an assignment: + is done before =.

Finally, I prefer not to use the negative "if x != y then foo else bar" 
because I find easier to understand "if x == y then bar else foo". Another 
alternative is to use "unless", which Chris seems not to have introduced in 
Chapter 6, but it means "if not". Same for while - "while keep_count != 3" 
is the same as "until keep_count == 3".

So here are my changes to your program all together:

keep_count = 0
until keep_count == 3
  input = gets.chomp
  if input == 'BYE'
    keep_count = keep_count + 1
    unless keep_count == 3
      puts 'HUH?! SPEAK UP, SONNY!'
    end
  else
    keep_count = 0
    puts 'HUH?! SPEAK UP, SONNY!'
  end
end
puts 'NO, NOT SINCE ' + (1930 + number).to_s + '!'

But, my understanding of the question must be different to yours. I 
understand the original should behave like this:
> Hello Grandma
HUH?!  SPEAK UP, SONNY!
> HELLO GRANDMA
NO, NOT SINCE 1938!
> WHAT HASN'T BEEN SINCE 1938?
NO, NOT SINCE 1945!
> BYE
BYE, BYE

And the 3-times one should be something like:
> Hello Grandma
HUH?!  SPEAK UP, SONNY!
> HELLO GRANDMA
NO, NOT SINCE 1938!
> BYE
HUH?!  SPEAK UP, SONNY!
> BYE
HUH?!  SPEAK UP, SONNY!
> BYE
BYE, BYE

I've written my solutions to these after some whitespace at the end of this 
message.

Cheers,
Dave










































# Deaf Grandma
input = gets.chomp
until input == "BYE"
  if input == input.upcase
    puts "NO, NOT SINCE " + (1930 + rand(21)).to_s + "!"
  else
    puts "HUH!? SPEAK UP, SONNY!"
  end
  input = gets.chomp
end
puts "BYE, BYE"

# Extra Deaf Grandma
byes = 0
input = gets.chomp
until byes == 3
  if input == "BYE"
    byes = byes + 1
  else
    byes = 0
  end
  if input == input.upcase
    puts "NO, NOT SINCE " + (1930 + rand(21)).to_s + "!"
  else
    puts "HUH!? SPEAK UP, SONNY!"
  end
  input = gets.chomp
end
puts "BYE, BYE"