File Word Counter

This tool will read a text file and count the number of words in it. This project is straightforward and a great way to practice file handling and basic string manipulation in Elixir. You can further adjust this tool to your usecase, like creating your own editor that will have a word count.

Here’s an outline of what we’ll cover:

Overview link

We’ll create a CLI tool named word_counter that reads a specified text file and counts the number of words in it. This tool will help users quickly determine the word count of a given file.

Setting Up the Project link

1. Create a new Elixir project:

  mix new word_counter
cd word_counter
  

Reading the File link

Create a module WordCounter in lib/word_counter.ex to handle file reading:

  defmodule WordCounter do
    def read_file(file_path) do
    case File.read(file_path) do
        {:ok, content} -> {:ok, content}
        {:error, reason} -> {:error, reason}
    end
    end
end
  

Counting Words link

Add a function to count words in the WordCounter module in lib/word_counter.ex:

  defmodule WordCounter do
  def read_file(file_path) do
    case File.read(file_path) do
      {:ok, content} -> {:ok, content}
      {:error, reason} -> {:error, reason}
    end
  end

  def count_words(content) do
    content
    |> String.split(~r/\s+/)
    |> length()
  end
end
  

Handling Command-line Arguments link

Create a module WordCounter.CLI in lib/word_counter/cli.ex to handle command-line interaction:

  defmodule WordCounter.CLI do
  def main(args) do
    case parse_args(args) do
      {:ok, file_path} -> process_file(file_path)
      {:error, message} -> IO.puts(message)
    end
  end

  defp parse_args([file_path]) when is_binary(file_path), do: {:ok, file_path}
  defp parse_args(_), do: {:error, "Usage: word_counter <file_path>"}

  defp process_file(file_path) do
    case WordCounter.read_file(file_path) do
      {:ok, content} ->
        word_count = WordCounter.count_words(content)
        IO.puts("The file contains #{word_count} words.")

      {:error, reason} ->
        IO.puts("Failed to read file: #{reason}")
    end
  end
end
  

Modify the mix.exs file to set the escript options so that the project can be run as a standalone executable:

  defmodule WordCounter.MixProject do
    use Mix.Project

    def project do
    [
        app: :word_counter,
        version: "0.1.0",
        elixir: "~> 1.11",
        start_permanent: Mix.env() == :prod,
        deps: deps(),
        escript: escript()
    ]
    end

    defp escript do
    [main_module: WordCounter.CLI]
    end

    defp deps do
    []
    end
end
  

Running the program link

Even though we don’t have any dependencies in this project, it’s always a good idea to run this command to ensure everything is up-to-date:

  mix deps.get
  

Now, running this command will produce and executable for the tool.

  mix escript.build
  

After that, run the executable with the path to your file. For this case, simple create a file named demo.txt on your root project, and run the following command:

  ./word_counter demo.txt
  

You should see and output like:

  The file contains 2 words.
  

Conclusion link

You’ve built a simple and useful CLI tool in Elixir that reads a text file and counts the number of words. This project demonstrates basic file handling, string manipulation, and command-line interaction in Elixir.

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