Basic CLI Calculator

The application tries to simulate the basic operations on a calculator like add, subtract, multiply and divide on the command line.

Install

This program runs on Ruby entirely, so, first you need to make sure you have it already installed on your machine. Sometimes in MacOS X and some Linux distributions already have Ruby installed out of the box. If thats not your case you can follow the official documentation and install it yourself.

To verify if you have a valid Ruby installed run this command on your terminal:

ruby -v

You will get something like this:

ruby 2.7.1p83 (2020-03-31 revision a0c7c23c9c) [x86_64-darwin18]

Any version of Ruby should work but it is recommended to install the latest one which righ now is 2.7.1.

Usage

To run the application, first, in your terminal run the following command to clone this repo:

$ git clone https://github.com/alexventuraio/basic_cli_calculator.git

Then access the folder with:

$ cd basic_calculator/

Now, run the entry point of the app with the next command:

$ ruby main.rb

At this point you will be able to see the Calculator mask in your terminal. 🎉🎉🎉

The values shown as buttons are the only values that are accepted:

Name	Code
0..9	Numbers from 0 tot 9
+,-,*,/	Supported operations
=	To get the running total
c	To clear memory out
q	To exit from the application

It is important that you enter values kind of the same that you do in a real calculator, one value at a time and pres ENTER between each selected key.

• For example: to calculate 3 + 2 - 4 = 1 you must type:

  3 ... enter
  + ... enter
  2 ... enter
  - ... enter
  4 ... enter
  = ... enter
  

• Also you can enter negative numbers in one shot like this: 3 * (-1) = -3

  3 ... enter
  * ... enter
  -1 ... enter
  = ... enter
  

• You can enter numbers in one shot or type one by one, for example, to enter 3245:

  3245 ... enter
  
  // ----- or -----
  
  3 ... enter
  2 ... enter
  4 ... enter
  5 ... enter
  

• Be awere that you are not allow to enter values like this: 44-1, you will get an error message.

Test suite

First, you need to make sure you have RSpec installed. As mentioned before, once you have ruby installed in your system, installing RSpec is pretty straightforward. Just run the following command inside the root folder of the application:

$ gem install rspec

Once your have RSpec in your system, you just have to execute the following command to run the entire test suite:

$ rspec