Standard telephone keypads contain the digits 0 through 9. The numbers 2 through 9 each have three letters associated with them, as indicated by the following table:
Digit Letter
2 A B C
3 D E F
4 G H I
5 J K L
6 M N O
7 P R S
8 T U V
9 W X Y
Many people find it difficult to memorize phone numbers, so they use the correspondence between digits and letters to develop seven-letter words that correspond to their phone numbers. For example, a person whose telephone number is 686-2377 might use the correspondence indicated in the above table to develop seven-letter word “NUMBERS”.
Business frequently attempt to get telephone numbers that are easy for their clients to remember. If a business can advertise a simple word for its customers to dial, then no doubt the business will receive a few more calls.
Each seven-letter word corresponds to exactly one seven-digit telephone number. The restaurant wishing to increase its take home business could surely do so with the number 825-3688 (i.e. “TAKEOUT”).
Each seven-digit phone number corresponds to many separate seven-letter words. Unfortunately, most of these represent unrecognizable juxtaposition of letters. It is possible, however, that the owner of a barber shop would be pleased to know that the shop’s telephone number, 424-7288 corresponds to “HAIRCUT”. The owner of a liquor store would, no doubt, be delighted to find that the store’s telephone, 233-7226, corresponds to “BEERCAN”. A veterinarian with the phone number 738-2273 would be pleased to know that the number corresponds to the letters “PETCARE”.
Write a C program that given a seven-digit number, writes to file every possible seven-letter word corresponding to that number. There are 2187 (3 to the seventh power) such words. Avoid phone number with digits 0 and 1. Create a separate file for every distinct seven-digit phone number. You need to repeat the process until a user signals to stop.
