Let's solve another problem.

WARNING: You will probably feel frustrated at solving these coding challenges - they can become quite difficult!

Square Each Digits

Given a number, write a method called square_each_digit to find out the square of each digit of the input. If the input is not a number, the program should return "NaN".

For example, 3211 should turn into 9411, 654326 to 3625169436, and "hello" should return "NaN".

Getting Started

First, navigate to the square_each_digit directory that you have downloaded in the previous lesson:

If you are on string_compressor directory, go back one step:

cd ..

And navigate to square_each_digit directory:

cd square_each_digit

Once you are in the folder in the terminal, run the following command:

rspec square_each_digit.rb

This will run some tests to see if your code is working. Since you haven't written any code yet, you will see that all of the tests fail. The output should look something like this:

Next, open up your text editor and open square_each_digit.rb

You should see code like this:

def square_each_digit num
  # Write your code here
end

describe "#square_each_digit" do
  context "it is a number" do
    it "returns square of each digit" do
      expect(square_each_digit(3211)).to eq(9411)
      expect(square_each_digit(654326)).to eq(3625169436)
      expect(square_each_digit(1111)).to eq(1111)
    end
  end

  context "it is not a number" do
    it "returns NaN" do
      expect(square_each_digit("hello")).to eq("NaN")
      expect(square_each_digit("12hello")).to eq("NaN")
    end
  end
end

For now you can ignore following codes:

describe "#square_each_digit" do
  context "it is a number" do
    it "returns square of each digit" do
      expect(square_each_digit(3211)).to eq(9411)
      expect(square_each_digit(654326)).to eq(3625169436)
      expect(square_each_digit(1111)).to eq(1111)
    end
  end

  context "it is not a number" do
    it "returns NaN" do
      expect(square_each_digit("hello")).to eq("NaN")
      expect(square_each_digit("12hello")).to eq("NaN")
    end
  end
end

Implement your solution in this file.

Once you have implemented the solution, go into your terminal and run this command again:

rspec

If your solution is correct, you should see an output like this:

Good luck!