HW2: Word Helper

Description

Write a C++ program called wh.cc that helps you match hangman or crossword-puzzle words.

Your program reads in a dictionary of words. The dictionary used in the sample run is here. It has the concept of a current “guess”, which is of a fixed length. Initially, all letters in the guess are undetermined, but some letters can be determined by the user.

Sample Runs

    % g++ wh.cc
    % ./a.out
    'h' for help
    ? l 5
    _____ has 0 matches.
    ? h
    l <len>: set length
    d <filename>: read a new dictionary
    a <letter> <positions>: add letter to the given positions
    w: show all words that match
    c: clear the guess to all underscores
    h: show this help listing
    q: quit
    _____ has 0 matches.
    ? d common-words.txt
    There are 4342 words.
    _____ has 687 matches.
    ? ae4
    ____e has 150 matches.
    ? a t0
    t___e has 12 matches.
    ? a h 1
    th__e has 5 matches.
    ? w
    these
    those
    theme
    three
    there
    th__e has 5 matches.
    ? ae2
    the_e has 3 matches.
    ? w
    these
    theme
    there
    the_e has 3 matches.
    ? r
    Invalid command!
    the_e has 3 matches.
    ? c
    _____ has 687 matches.
    ? q

Requirements

Dictionary

There is no limit to the number of words in the dictionary.
There is no limit to the length of a word.
Words don’t have to be just a-z. For example, “don’t”, “bone-head”, and “CS253” are valid words.
Words will not contain spaces or underscores.
The dictionary contains one word per line.
Reading another dictionary is permitted. This replaces the words from the previous dictionary. This does not reset the length of the guess, or reset the guess itself.
You may assume that the dictionary will not contain duplicate words.

The guess

Resetting the length resets the guess, as if the c command were given.
The behavior of this program is unspecified until the l command is given, except as shown in the example above.

The a command

The <positions> in the a command are a space-separated list of integers.
When the a command says <letter>, it means one letter a-z or A-Z.

Errors

Emit an error message to standard error and continue if the dictionary file can’t be read. This makes the number of words zero.
Emit an error message to standard error and continue if an invalid command is given, or a command gets invalid arguments, including:
- the command “z”
- the command “w 5”
- the command “a x 99” if the length is 5
- the command “a z 4x”
- the command “a % 4”
- the command “quaff”
- the command “Q”

Miscellaneous

Spaces are optional in the l, d, and a commands.
It’s ok to emit the ungrammatical “has 1 matches”.
Using the .eof() method will result in the loss of several points.
You may not use external commands. grep would make this too easy.

If you have any questions about the requirements, ask. In the real world, your programming tasks will almost always be vague and incompletely specified. Same here.

Turning it in

How to submit your homework:

Follow the instructions on the Homework page

How to receive negative points:

Turn in someone else’s work.

CS253: Problem Solving with C++

Spring 2013

HW 2