Catch and throw not working in ruby - ruby

Question

I am trying to make a number guessing game in Ruby but the program exits after I type in yes when I want to play again. I tried using the catch and throw but it would not work. Could I please get some help.
Here is my code.
class Game
def Play
catch (:start) do
$a=rand(11)
puts ($a)
until $g==$a
puts "Guess the number between 0-10."
$g=gets.to_i
if $g>$a
puts "The number you guessed is too high."
elsif $g==$a
puts "Correct you won!!!"
puts "Would you like to play again?"
$s=gets()
if $s=="yes"
$c=true
end
if $c==true
throw (:start)
end
elsif $g<$a
puts "The number you guessed is too low."
end
end
end
end
end
Game.new.Play
Edit: Here's my new code after trying suggestions:
class Game
def Play
catch (:start) do
$a=rand(11)
puts ($a)
while $s=="yes"
until $g==$a
puts "Guess the number between 0-10."
$g=gets.chomp.to_i
if $g>$a
puts "The number you guessed is too high."
elsif $g==$a
puts "Correct you won!!!"
puts "Would you like to play again?"
$s=gets.chomp
if $s=="yes"
throw (:start)
end
elsif $g<$a
puts "The number you guessed is too low."
end
end
end
end
end
end
Game.new.Play

Answer 1

Your first problem is here:
$s=gets()
if $s=="yes"
$c=true
end
The gets method will read the next line including the new line character '\n', and you compare it to only "yes":
> gets
=> "yes\n"
The idiomatic way to fix this in Ruby is the chomp method:
> gets.chomp
=> "yes"
That said, your code has two other deficiencies.
You may come from a language such as PHP, Perl, or even just Bash scripting, but Ruby doesn't require the dollar sign before variables. Using a $ gives a variable global scope, which is likely not what you want. In fact, you almost never want a variable to have global scope.
Ruby uses three types of symbol prefixes to indicate scope - # for instance, ## for class, and $ for global. However the most common type of variable is just local which doesn't need any prefix, and what I would suggest for your code.
I have always been told that it is very bad practice to use exceptions for control structure. Your code would be better served with a while/break structure.

Answer 2

When you do gets(), it retrieves the full line with a '\n' in the end. You need to trim the new line character by using:
$g=gets.chomp.to_i
Same for other gets

Answer 3

Based on your updated code (where you fixed the newline problem shown by others), your new problem is that you have wrapped all your game inside while $s=="true". The very first time your code is run, $s is nil (it has never been set), and so you never get to play. If you used local variables instead of global variables (s instead of $s) this would have become more obvious, because the code would not even have run.
Here's one working way that I would re-write your game.
class Game
def play
keep_playing = true
while keep_playing
answer = rand(11) # Make a new answer each time
puts answer if $DEBUG # we don't normally let the user cheat
loop do # keep going until I break from the loop
puts "Guess the number between 0-10."
guess = gets.to_i # no need for chomp here
if guess>answer
puts "The number you guessed is too high."
elsif guess<answer
puts "The number you guessed is too low."
else
puts "Correct you won!!!",
"Would you like to play again?"
keep_playing = gets.chomp.downcase=="yes"
break
end
end
end
end
end
Game.new.play

Answer 4

I know this doesn't really answer your question about why your code isn't working, but after seeing the code you posted I just had to refactor it. Here you go:
class Game
def initialize
#answer = rand(11)
end
def play
loop do
guess = get_guess
display_feedback guess
break if guess == #answer
end
end
def self.play_loop
loop do
Game.new.play
break unless play_again?
end
end
private
def get_guess
puts "Guess the number between 0-10."
return gets.chomp.to_i
end
def display_feedback(guess)
if guess > #answer
puts "The number you guessed is too high."
elsif guess < #answer
puts "The number you guessed is too low."
elsif guess == #answer
puts "Correct you won!!!"
end
end
def self.play_again?
puts "Would you like to play again?"
return gets.chomp == "yes"
end
end
Game.play_loop