Say

Instructions

Given a number, your task is to express it in English words exactly as your friend should say it out loud. Yaʻqūb expects to use numbers from 0 up to 999,999,999,999.

Examples:

• 0 → zero
• 1 → one
• 12 → twelve
• 123 → one hundred twenty-three
• 1,234 → one thousand two hundred thirty-four

Rust Specific Exercise Notes

This is slightly changed in the Rust version, compared to other language versions of this exercise. Instead of requiring you to return errors for out of range, we are using Rust's strong type system to limit input. It is much easier to make a function deal with all valid inputs, rather than requiring the user of your module to handle errors.

Extension

Add capability of converting up to the max value for u64: 18_446_744_073_709_551_615.

For hints at the output this should have, look at the last test case.

---

Source

A variation on the JavaRanch CattleDrive, Assignment 4