Number Guessing game in Ruby

In this tutorial, we are building a simple number guessing game where computer will choose any random number between 1 to 100.

Then, we need to ask user to guess the correct number. Maximum allowed guessing is 10.

If the user failed to enter the correct number then display the hints as following:

• “Your guess was low, enter a higher number.” when guessed number is less than correct number.
• “Your guess was high, enter a lower number.” when guessed number is greater than correct number.

Demo

Prerequisites

• Enthusiasm and passion to Learn
• Basic knowledge of Ruby language
  • Variables
  • Loop
  • Conditional Operators
  • Getting input from User

Solution Steps

Follow the steps below to build the Number Guessing game in Ruby.

• Before even asking user, let’s generate a random number random_num.

  random_num = rand(100)
  

• Let’s create a variable to track number of guess a user can make.

  num_of_guesses = 0
  

• Let’s ask user his or her name.

  print("Hey, may I know your first name? ")
  # puts will add new line so print should be used
  name = gets.chomp          # remove the extra new line character
  name = name.capitalize()   # make the first letter capital
  

• Until the number of guess is less than maximum allowed guess i.e 10, repeat guessing number, compare it with actual number and print the hint accordingly. If you found guess number is equal to actual number then break out of loop.

  while num_of_guesses < 10
    print("\nGuess a number from 1 to 100: ")
    guess_num = gets.to_i
    # gets return as string datatype, hence we need to convert to integer
  
    num_of_guesses = num_of_guesses + 1
    # you can write above as num_of_guesses += 1
    guesses_left = (10 - num_of_guesses)
  
    if guess_num < random_num
      puts("#{name}, your guess was low, enter a higher number. You have #{guesses_left} guesses left.")
    elsif guess_num > random_num
      puts("#{name}, your guess was high, enter a lower number. You have #{guesses_left} guesses left.")
    end
  
    break if guess_num == random_num
  end
  

• Now, print the final message and number of guess taken.

  if guess_num == random_num
    puts("Good job, #{name}! You guessed the number in #{num_of_guesses} tries.")
  else
    puts("#{name}, you failed to guess correctly. Actual number is #{random_num}.")
  end
  

Solution

# number_guess.rb
random_num = rand(100)  # generate a random number
num_of_guesses = 0  # store number of guesses

print("Hey, may I know your first name? ")
name = gets.chomp          # remove the extra new line character
name = name.capitalize()   # make the first letter capital

while num_of_guesses < 10
  print("\nGuess a number from 1 to 100: ")
  guess_num = gets.to_i
  # gets return as string datatype, hence we need to convert to integer

  num_of_guesses = num_of_guesses + 1
  # you can write above as num_of_guesses += 1
  guesses_left = (10 - num_of_guesses)

  if guess_num < random_num
    puts("#{name}, your guess was low, enter a higher number. You have #{guesses_left} guesses left.")
  elsif guess_num > random_num
    puts("#{name}, your guess was high, enter a lower number. You have #{guesses_left} guesses left.")
  end

  break if guess_num == random_num
end

if guess_num == random_num
  puts("Good job, #{name}! You guessed the number in #{num_of_guesses} tries.")
else
  puts("#{name}, you failed to guess correctly. Actual number is #{random_num}.")
end

Possible optimizations

Following are the possible optimization which you can do by yourself:

• You can create a class NumberGuess and then write a play method to make the solution Object Oriented.
• There are repeated text in messages like your guess is low or high, enter a lower or higher now ....