https://github.com/stokito/rpn-calc

Java RPN calculator example
https://github.com/stokito/rpn-calc

assignment job-assignment rpn-calculator

Last synced: 18 days ago
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Java RPN calculator example

• Host: GitHub
• URL: https://github.com/stokito/rpn-calc
• Owner: stokito
• License: mit
• Created: 2020-04-02T11:09:01.000Z (almost 5 years ago)
• Default Branch: master
• Last Pushed: 2023-04-26T19:17:32.000Z (over 1 year ago)
• Last Synced: 2024-12-13T01:33:14.300Z (23 days ago)
• Topics: assignment, job-assignment, rpn-calculator
• Language: Java
• Homepage:
• Size: 23.4 KB
• Stars: 1
• Watchers: 3
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE.txt

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README

        
# CLI RPN Calculator

The command-line [Reverse Polish Notation (RPN)](https://en.wikipedia.org/wiki/Reverse_Polish_notation) calculator.

Was developed as a [test task](https://gist.github.com/joedean/078a62b9ec03b38dfc519b3a5f168b07).

## Specifications

* The calculator should use standard input and standard output

* It should implement the four standard arithmetic operators

* The calculator should handle errors and recover gracefully

* The calculator should exit when it receives a `q` command or an end of input indicator (`EOF` / `Ctrl+D`)

 

`py` op

1. A^2 + B^2 = C^2

5 12 13 = true

## Build and run

You need a JDK 13 or later and Maven. To build run `mvn clean package`.

The executable jar will be built and placed into `target/rpn-calc.jar`.

To run it use:

    java -jar target/rpn-calc.jar

Then it will prompt for an input with a line started with `> `.

## Usage

For example to calculate an expression `5 / (9 - 1) = 0.625` write each number (operand) and press Enter then write an arithmetic command (operator):  

    > 5

    5

    > 9

    9

    > 1

    1

    > -

    8

    > /

    0.625

    >

The last number is your result. You can use a single line input:

    > 5 9 1 - /

    0.625

To exit the program you can input command `quit` or simply `q`.

You can also use other commands for example `debug` or `d` to see the values stack and `clear` or `c` to remove everything from the stack:

    > 1

    1

    > 2

    2

    > 3

    3

    > d

    3

    2

    1

    > c

    > d

    >

The calculator also have other functions from `java.lang.Math` and to see them use a command `help` or `h`:

    > h

    *

    +

    -

    /

    IEEEremainder

    abs

    acos

    asin

    atan

    atan2

    cbrt

    ceil

    copySign

    cos

    cosh

    exp

    expm1

    floor

    hypot

    log

    log10

    log1p

    max

    min

    neg

    nextAfter

    nextDown

    nextUp

    pow

    rint

    signum

    sin

    sinh

    sqrt

    tan

    tanh

    toDegrees

    toRadians

    ulp

    >

For example to calculate square root and negate it:

    > 4

    4

    > sqrt

    2

    > neg

    -2

    >

## Implementation

The core of the calculator is `Calc` class which contains the values stack and performs all the calculations.

The class designed in a JavaBeans style and have getters and setters so can be easily used with DI.

The actual parsing and interaction with a user via the command line performed by the `StreamProcessor` class.

You can extend the calc and add your custom operator by extending `CalcUnaryOp` or `CalcBinaryOp`. Then you'll need to add them into `Ops.BASIC_OPS` list or this can be done with DI.

Internally the calculator uses a `double` type so all the calculations have the same issues as IEEE-754 float numbers have.