CS 162, Spring 2003
Programming Assignment 4
Due: Wednesday, May 5

Words to Numbers

For this assignment we are going back to a text based interface. Read a list of integer numbers from the standard input until end of file is encountered. As each number is read, the textual representation of the number is printed. The numbers must be in the range of Java integers (-2147483648 to 2147483647). Here are some examples of what I mean by textual names: zero, negative three, two billion one hundred forty seven million four hundred eighty three thousand six hundred forty seven.

To convert a number to a string is pretty easy, if you think recursively. Here are some hints:

• Almost all negative numbers can be handled by prepending the word "negative" and then calculating the corresponding positive value. I leave it to you to figure out why I say "almost all".
• We're american, not british, so our billion is a thousand million, not a million million as it is in England. If a number if bigger than a billion, figure out how many billions it is, and the remainder after the billion part, and then recursively put the two together.
• Ditto for millions and thousands and hundreds.
• ninetys, eighties, and so on down to 20's are handled by producing the place name (such as eighty) and a recursive call to get the remainder.
• The values 0 to 19 are handled as special cases.

You MUST solve this problem recursively. (Actually, you would be silly not to).

Here is an interesting question. If all the names for the legal Java integers were listed in a dictionary, which would be the first entry? What would be the last entry? What entry would have the most characters? Useless brownie points for the first people to come up with the answers to these questions.