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58 lines
2.3 KiB
58 lines
2.3 KiB
# Calculator
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**Tier:** 1-Beginner
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Calculators are not only one of the most useful tools available, but they are
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also a great way to understand UI and event processing in an application. In
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this problem you will create a calculator that supports basic arithmetic
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calculations on integers.
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The styling is up to you so use your imagination and get creative! You might
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also find it worth your time to experiment with the calculator app on your
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mobile device to better understand basic functionality and edge cases.
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### Constraints
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- You may not use the `eval()` function to execute calculations
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## User Stories
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- [ ] User can see a display showing the current number entered or the
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result of the last operation.
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- [ ] User can see an entry pad containing buttons for the digits 0-9,
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operations - '+', '-', '/', and '=', a 'C' button (for clear), and an 'AC'
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button (for clear all).
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- [ ] User can enter numbers as sequences up to 8 digits long by clicking on
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digits in the entry pad. Entry of any digits more than 8 will be ignored.
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- [ ] User can click on an operation button to display the result of that
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operation on:
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* the result of the preceding operation and the last number entered OR
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* the last two numbers entered OR
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* the last number entered
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- [ ] User can click the 'C' button to clear the last number or the last
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operation. If the users last entry was an operation the display will be
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updated to the value that preceded it.
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- [ ] User can click the 'AC' button to clear all internal work areas and
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to set the display to 0.
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- [ ] User can see 'ERR' displayed if any operation would exceed the
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8 digit maximum.
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## Bonus features
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- [ ] User can click a '+/-' button to change the sign of the number that is
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currently displayed.
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- [ ] User can see a decimal point ('.') button on the entry pad to that
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allows floating point numbers up to 3 places to be entered and operations to
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be carried out to the maximum number of decimal places entered for any one
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number.
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## Useful links and resources
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- [Calculator (Wikipedia)](https://en.wikipedia.org/wiki/Calculator)
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- [MDN](https://developer.mozilla.org/en-US/)
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## Example projects
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- [Javascript Calculator](https://codepen.io/giana/pen/GJMBEv)
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- [React Calculator](https://codepen.io/mjijackson/pen/xOzyGX)
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