 # ChrisPritchard's solution

## to Say in the C# Track

Published at Oct 05 2018 · 0 comments
Instructions
Test suite
Solution

#### Note:

This exercise has changed since this solution was written.

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.

## 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".

## Source

A variation on JavaRanch CattleDrive, exercise 4a 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.

### SayTest.cs

``````// This file was auto-generated based on version 1.1.0 of the canonical data.

using System;
using Xunit;

public class SayTest
{
[Fact]
public void Zero()
{
Assert.Equal("zero", Say.InEnglish(0));
}

[Fact(Skip = "Remove to run test")]
public void One()
{
Assert.Equal("one", Say.InEnglish(1));
}

[Fact(Skip = "Remove to run test")]
public void Fourteen()
{
Assert.Equal("fourteen", Say.InEnglish(14));
}

[Fact(Skip = "Remove to run test")]
public void Twenty()
{
Assert.Equal("twenty", Say.InEnglish(20));
}

[Fact(Skip = "Remove to run test")]
public void Twenty_two()
{
Assert.Equal("twenty-two", Say.InEnglish(22));
}

[Fact(Skip = "Remove to run test")]
public void One_hundred()
{
Assert.Equal("one hundred", Say.InEnglish(100));
}

[Fact(Skip = "Remove to run test")]
public void One_hundred_twenty_three()
{
Assert.Equal("one hundred twenty-three", Say.InEnglish(123));
}

[Fact(Skip = "Remove to run test")]
public void One_thousand()
{
Assert.Equal("one thousand", Say.InEnglish(1000));
}

[Fact(Skip = "Remove to run test")]
public void One_thousand_two_hundred_thirty_four()
{
Assert.Equal("one thousand two hundred thirty-four", Say.InEnglish(1234));
}

[Fact(Skip = "Remove to run test")]
public void One_million()
{
Assert.Equal("one million", Say.InEnglish(1000000));
}

[Fact(Skip = "Remove to run test")]
public void One_million_two_thousand_three_hundred_forty_five()
{
Assert.Equal("one million two thousand three hundred forty-five", Say.InEnglish(1002345));
}

[Fact(Skip = "Remove to run test")]
public void One_billion()
{
Assert.Equal("one billion", Say.InEnglish(1000000000));
}

[Fact(Skip = "Remove to run test")]
public void A_big_number()
{
Assert.Equal("nine hundred eighty-seven billion six hundred fifty-four million three hundred twenty-one thousand one hundred twenty-three", Say.InEnglish(987654321123));
}

[Fact(Skip = "Remove to run test")]
public void Numbers_below_zero_are_out_of_range()
{
Assert.Throws<ArgumentOutOfRangeException>(() => Say.InEnglish(-1));
}

[Fact(Skip = "Remove to run test")]
public void Numbers_above_999_999_999_999_are_out_of_range()
{
Assert.Throws<ArgumentOutOfRangeException>(() => Say.InEnglish(1000000000000));
}
}``````
``````﻿using System;
using System.Linq;
using System.Collections.Generic;

public static class Say
{
public static string InEnglish(long number)
{
if(number < 0 || number > Math.Pow(10, 12) - 1)
throw new ArgumentOutOfRangeException();
if (number == 0)
return "zero";

return UnderTrillion(number);
}

private static (long, long) Divide (long number, int power)
{
var devisor = (long)Math.Pow(10.0, power);
return (number / devisor, number % devisor);
}

private static readonly Dictionary<long, string> underTwentyNames =
new (long number, string name)[]
{ (1, "one"), (2, "two"), (3, "three"), (4, "four"), (5, "five"),
(6, "six"), (7, "seven"), (8, "eight"), (9, "nine"), (10, "ten"),
(11, "eleven"), (12, "twelve"), (13, "thirteen"), (14, "fourteen"), (15, "fifteen"),
(16, "sixteen"), (17, "seventeen"), (18, "eighteen"), (19, "nineteen") }
.ToDictionary(o => o.number, o => o.name);

private static readonly Dictionary<long, string> underHundredPrefixes =
new (long number, string name)[]
{ (2, "twenty-"), (3, "thirty-"), (4, "forty-"), (5, "fifty-"),
(6, "sixty-"), (7, "seventy-"), (8, "eighty-"), (9, "ninety-") }
.ToDictionary(o => o.number, o => o.name);

private static string UnderTwenty(long number)
=> underTwentyNames.GetValueOrDefault(number, "");

private static string UnderHundred(long number)
{
var (tens, remainder) = Divide(number, 1);
if (tens < 2)
return UnderTwenty(number);

var prefix = underHundredPrefixes.GetValueOrDefault(tens, "");
var name = UnderTwenty(remainder);
return \$"{prefix}{name}".TrimEnd('-');
}

private static string UnderThousand(long number)
{
var (hundreds, remainder) = Divide(number, 2);
if(hundreds == 0)
return UnderHundred(number);
return \$"{UnderTwenty(hundreds)} hundred {UnderHundred(remainder)}".Trim();
}

private static string UnderMillion(long number)
{
var (thousands, remainder) = Divide(number, 3);
if(thousands == 0)
return UnderThousand(number);
return \$"{UnderThousand(thousands)} thousand {UnderThousand(remainder)}".Trim();
}

private static string UnderBillion(long number)
{
var (millions, remainder) = Divide(number, 6);
if(millions == 0)
return UnderMillion(number);
return \$"{UnderThousand(millions)} million {UnderMillion(remainder)}".Trim();
}

private static string UnderTrillion(long number)
{
var (billions, remainder) = Divide(number, 9);
if(billions == 0)
return UnderBillion(number);
return \$"{UnderThousand(billions)} billion {UnderBillion(remainder)}".Trim();
}
}``````