Objective

1. To give students practice writing functions.
2. To give students practice using C strings.
3. To give students practice utilizing an array of strings (two dimensional array).


Problem: Spell Checker

Many of us have horrible spelling and would get great practical use out of a spell-checker. In this assignment, you will write a simplified version of a spell checker. In the process, you will write several of your own string functions.


Implementation Details: string functions to write

Note: Assume that all of the formal parameters for each of the functions below are lowercase alphabetic strings.

A string is a substring of another one if all of its letters appear contiguously (in the same order) in the second string. For example, “bound” is a substring of “homebound” and “ire” is a substring of “firefly”, but “car” is NOT a substring of “camera” because the letters ‘m’ and ‘e’ are in between the letters ‘a’ and ‘r’ in “camera.”

// Returns true if shortstr is a substring of longstr,
// and false otherwise.
int substring(char shortstr[], char longstr[]);

A string is a subsequence of another string if all the letters in the first string appear in the second string, in the same ordering, but not necessarily contiguously. For example, “car” is a subsequence of “camera”, since the letters ‘c’,’a’, and ‘r’ appear in that order (but not contiguously) in “camera.” Similarly, “hikes” is a subsequence of “chickens,” but “tale” is NOT a subsequence of “wallet” because the letter ‘t’ occurs AFTER the letter ‘a’ in “wallet.”

// Returns true if shortstr is a subsequence of longstr,
// and false otherwise.
int subsequence(char shortstr[], char longstr[]);


A permutation of letters is simply a different ordering of those letters. For example, “care” is a permutation of “race” and “spill” is a permutation of “pills,” but “apple” is NOT a permutation of “pale” because the letter ‘p’ appears only once instead of twice in “pale.” A natural consequence of this definition is that two strings can only be permutations of one another if they are both the same length.

// Returns true if string1 and string2 are permutatations
// of each other, false otherwise.
int permutation(char string1[], char string2[]);

When we are comparing two strings of equal length, we can define a term called “match score” which is simply the number of corresponding letters in which the two strings disagree. For example, the match score between “drink” and “blank” is 3 because the first three letters don’t match. The match score between “marker” and “master” is two because letters 3 (r vs. s) and 4 (k vs. t) do not match.

// Precondition: string1 and string2 are the same length
// and only contain lowercase letters.
// Postcondition: returns the score of the match score
// between these two strings.
int matchscore(char string1[],char string2[]);


Input File Format(dictionary.txt)

The first line of the file will have a single positive integer, n (n ≤ 30000), representing the number of words in the file. The following n lines will contain one word each, in alphabetic order. All words will contain lowercase letters only and will be no longer than 29 letters long.

Here is a short sample dictionary:

5
apple
boat
car
dog
elephant


What your program should do

Your program should first read in the dictionary into a two-dimensional character array (from dictionary.txt) and print a message to the screen stating that the dictionary has been loaded.

Then your program should prompt the user to enter a word, all lowercase.

If the word is in the dictionary, you should simply print out a message stating this.

If the word is NOT in the dictionary, then you should provide a list of possible suggestions (of correctly spelled words that the user might have been trying to spell) in alphabetical order.

Here are the criteria for whether or not a real word should end up on this list:

1) If either string is a substring of the other, and the lengths of the two strings are within 2 of one another.
2) If either string is a subsequence of the other and the lengths of the two strings are within 2 of one another. (This would get rid of the “car”, “camera” case, for example.)
3) If the strings are permutations of one the other. (Only try this test if the two strings are of the same length.)
4) If the matchscore between the two strings is less than 3. (Only try this test if the two strings are of the same length.)

Continue prompting the user to enter words until they decide that they don’t want to enter any more. (Thus, they will be forced to enter the first word, but after that, you’ll provide them a choice as to whether or not they want to enter another word to check.

References
Textbook: Chapters 8, 9, 11, 13 Notes: Lectures on functions, arrays
and strings.

Restrictions
Name the file you create and turn in spellcheck.c. Although you may use other compilers, your program must compile and run using Dev C++. Your program should include a header comment with the following information: your name, course number, section number, assignment title, and date. You should also include comments throughout your code, when appropriate. If you have any questions about this, please see a TA.


Deliverables
A single source file named spellcheck.c turned in through WebCourses.

Sample Output (with a real dictionary)
Welcome to the Spell Checker!
The dictionary has been loaded.

Please enter the word you would like checked.
flag

Great, flag is in the dictionary!

Would you like to enter another word? (yes/no)
yes

Please enter the word you would like checked.
peice

Here are the possible words you could have meant:

alice
beige
brice
deuce
fense
heince
hense
ice
juice
paine
peace
peach
peale
pease
pee
pence
perch
percy
perle
peste
pewee
pie
piece
place
poise
ponce
price
prick
pride
prime
prize
reich
seize
slice
spice
twice
voice

Would you like to enter another word? (yes/no)
yes

Please enter the word you would like checked.
independant

Here are the possible words you could have meant:

independent

Would you like to enter another word? (yes/no)
no

heck, if someone wants to just write the code for me(preferably with comments that would show me whats going on so i can learn it myself) i'd pay them in mesos, but to a degree would rather do it myself to learn this stuff, life is just hectic and finding time to learn is getting harder.