Ruby (Rock, Paper, Scissors)

Question

Hey I am new to ruby and I have sat for a long time trying to find out what I've done wrong in this code, there isn't any error but it isn't giving me my desired output as a normal game of rock paper scissors. Here is my code:

puts "Rock, Paper or Scissors"
choice = gets.chomp
cchoice = ["Rock", "Paper","Scissors"]
comp = rand(1..3)
won = false


puts "Computer chose #{cchoice[comp]}"
if (choice == "Rock")
    if (comp == 2)
        won = false
    end
    if (comp == 3)
        won = true
    end
elsif (choice == "Paper")
    if (comp == 3)
        won = false
    end
    if (comp == 1)
        won = true
    end
elsif (choice == "Scissors")
    if (comp == 1)
        won = false
    end
    if (comp == 2)
        won = true
    end
else
    puts "I dont know what that means so-"
end

if (won)
    puts "YOU WON!!!"
else
    puts "You lost.."
end

Thanks for any help!

Answer 1

The rules of rock, paper, scissors can be expressed as a simple hash:

conditions = {
  "Rock" => "Scissors",
  "Paper" =>  "Rock",
  "Scissors" => "Paper"
}

So you can simply check if one player won over the other with:

if conditions[player_1] == player_2
  puts "Player one wins!"
elsif player_1 == player_2
  puts "Its a draw!"
else
  puts "Player two wins!"
end

This is far less complex then a tree of nested if/else statements.

conditions = {
  "Rock" => "Scissors",
  "Paper" => "Rock",
  "Scissors" => "Paper"
}

puts "Rock, Paper or Scissors"
choice = gets.chomp.capitalize
cchoice = conditions.keys.sample
puts "Computer chose #{ cchoice }"
  
if conditions[choice] == cchoice
  puts "You won!"
elsif cchoice == choice
  puts "Its a draw."
elsif conditions[cchoice] == choice
  puts "You lost."
else
  puts "#{choice} is not a valid option"
end

This covers the four potential outcomes which are:

• win
• loss
• draw
• bad input (this could also be handled with controll flow like break/throw/catch)

Also instead of rand you can use Array#sample to select a random element from the keys of the hash which avoids the need to use array indices.

Answer 2

Your random number generator generates numbers between 1-3, it should be between 0-2 since you are trying to index a list

comp = rand(0..2)

Also change the comparison in the if clause to reflect the above change,

Another thing you might have forgot is the draw condition (if both select the same thing)