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exercism/python/say/README.md
2019-07-17 14:35:25 -05:00

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# Say
Given a number from 0 to 999,999,999,999, spell out that number in English.
## Step 1
Handle the basic case of 0 through 99.
If the input to the program is `22`, then the output should be
`'twenty-two'`.
Your program should complain loudly if given a number outside the
blessed range.
Some good test cases for this program are:
- 0
- 14
- 50
- 98
- -1
- 100
### Extension
If you're on a Mac, shell out to Mac OS X's `say` program to talk out
loud. If you're on Linux or Windows, eSpeakNG may be available with the command `espeak`.
## Step 2
Implement breaking a number up into chunks of thousands.
So `1234567890` should yield a list like 1, 234, 567, and 890, while the
far simpler `1000` should yield just 1 and 0.
The program must also report any values that are out of range.
## Step 3
Now handle inserting the appropriate scale word between those chunks.
So `1234567890` should yield `'1 billion 234 million 567 thousand 890'`
The program must also report any values that are out of range. It's
fine to stop at "trillion".
## Step 4
Put it all together to get nothing but plain English.
`12345` should give `twelve thousand three hundred forty-five`.
The program must also report any values that are out of range.
### Extensions
Use _and_ (correctly) when spelling out the number in English:
- 14 becomes "fourteen".
- 100 becomes "one hundred".
- 120 becomes "one hundred and twenty".
- 1002 becomes "one thousand and two".
- 1323 becomes "one thousand three hundred and twenty-three".
## Exception messages
Sometimes it is necessary to raise an exception. When you do this, you should include a meaningful error message to
indicate what the source of the error is. This makes your code more readable and helps significantly with debugging. Not
every exercise will require you to raise an exception, but for those that do, the tests will only pass if you include
a message.
To raise a message with an exception, just write it as an argument to the exception type. For example, instead of
`raise Exception`, you should write:
```python
raise Exception("Meaningful message indicating the source of the error")
```
## Running the tests
To run the tests, run the appropriate command below ([why they are different](https://github.com/pytest-dev/pytest/issues/1629#issue-161422224)):
- Python 2.7: `py.test say_test.py`
- Python 3.4+: `pytest say_test.py`
Alternatively, you can tell Python to run the pytest module (allowing the same command to be used regardless of Python version):
`python -m pytest say_test.py`
### Common `pytest` options
- `-v` : enable verbose output
- `-x` : stop running tests on first failure
- `--ff` : run failures from previous test before running other test cases
For other options, see `python -m pytest -h`
## Submitting Exercises
Note that, when trying to submit an exercise, make sure the solution is in the `$EXERCISM_WORKSPACE/python/say` directory.
You can find your Exercism workspace by running `exercism debug` and looking for the line that starts with `Workspace`.
For more detailed information about running tests, code style and linting,
please see [Running the Tests](http://exercism.io/tracks/python/tests).
## Source
A variation on JavaRanch CattleDrive, exercise 4a [http://www.javaranch.com/say.jsp](http://www.javaranch.com/say.jsp)
## Submitting Incomplete Solutions
It's possible to submit an incomplete solution so you can see how others have completed the exercise.