The Objective

The purpose of this assignment is to give you practice with recursion, strings and chars, string and char library functions, arrays of strings, allocating memory dynamically, reading files, and using command line arguments.

The Background

According to Webster's dictionary a palindrome is defined as a word or sentence that is the same whether read forward or backward, coming from the roots palin which means back and drome which means running on.

The Task

Your assignment will be to determine whether a given word, phrase or sentence is a palindrome. We will be providing a data file containing many phrases, some of which are palindromes. You will also give the user the option to look at some other statistics about each string: the number of vowels and consonants, the length of the string, and how many words each contains.

Program Requirements

• Your program must take the name of the text file to analyze as a command-line argument. The file that contains the strings is located on the GL system in the directory

  /afs/umbc.edu/users/b/o/bogar/pub

  The file is named strings.dat .

  You should copy this file from this location into the directory you will be using to work on this project. Do NOT cut and paste from this link, since you may inadvertently alter the file by doing so.

• You will open the file, read from it, and close it using C's file-handling functions.

• You will be storing these strings in an array of strings, for which you must dynamically allocate memory. Since an array of strings is really just an array of pointers to chars, you must also dynamically allocate the memory necessary to store the characters of each string.
  HINT:The addresses of the memory allocated for each of the strings are what is stored as the elements of the array of strings. See the drawing of the array of strings called months in lecture 16, on the Arrays of Pointers slide for a good visualization.

• Before continuing on to the more fun stuff, PRINT OUT what you actually managed to store in the array to make sure your reading, memory allocation and data storage into that memory was successful (i.e., still meaningful).

• You will be using a two-level menu system in your program to first allow the user to choose a string (1st level) and then allow the user to choose which statistics to view (2nd level).
  Menu specifications:
  • The 1st-level menu must display a numbered list of the strings. The user is to choose a string by entering its number, or may end the program by entering a 0.
  • The 2nd-level menu displays the string the user has chosen and then displays a menu of string statistics from which the user may choose. Each of the choices has an associated character that the user must enter, or Q to quit analysing the current string choice. You are REQUIRED to use single-character input for this menu, and the choices are to be:
    P to test for a palindrome
    V to report the number of vowels
    C to report the number of consonants
    L to report the length of the string
    W to report the number of words
    Q (for quit)to return to the 1st-level menu

    This menu must accept both lower and upper case entries of these letters and reject all others.

  • HINT:Since you now have a menu that must accept character input, you must make sure that you have read all of the characters from stdin before trying to read the character the user has just entered. This means the newline character the user entered after the digit from the first menu as well as the newline character entered after each character choice. You may NOT use fflush() to flush the buffer, since fflush was designed to work with output buffers and its behavior is unpredictable for input buffers like stdin.
  • Obviously, after the user has chosen from the 2nd-level menu, you should perform the necessary operation and report the result and again display the 2nd-level menu until the user chooses Q or q, which returns you to the 1st-level menu. At that time the user may choose another string to examine or choose 0 to end the program.

• You must have a recursive function called IsPalindrome() which determines whether the string passed to it is a palindrome. It must work recursively by calling itself with different arguments and may NOT have any loops within it. It should return either TRUE or FALSE, since it is a recursive predicate function. When determining whether a string is a palindrome, you should ignore white space characters, punctuation or any other characters that are not alphabetic. You should consider the upper-case and lower-case versions of the same letter to be the same letter. (i.e. they are equal).

• Since you will open the file, you must also close it, and you should do this as soon as you are finished reading from it.

• Do NOT use the function feof() to locate the end of the file. See the example for reading from a file using fgets() in lecture #15 on I/O.

• Since you are dynamically allocating memory both for the array of strings and the memory for each of the strings, you will need to free this memory. Simply saying free(array); will NOT free all of the memory that you have dynamically allocated, because it will not free the memory that you allocated for each of the strings.

• You must use separate compilation for this project.

Other Hints & Guarantees

• You will be reading the entire contents of the file into an array of strings. You must dynamically allocate enough space to hold that array, but you don't know how big to make it. - You could open the file and read one string at a time until you hit the end of the file keeping count of the number of strings as you go. You can get back to the beginning of the file by using rewind().

• Notice in the output that the number of vowels or consonants is the total number of times a vowel or consonant occurs in the string, whether it be upper or lower case and regardless of whether that specific vowel or consonant was previously encountered in the string. The CountVowels() function should count the total number of vowels, not the total number of unique vowels. (There is no function in the ctype library for counting vowels. You'll have to write a function for this yourself.)

• We guarantee that each string in the file will end with a newline character and that the strlen() of no string will exceed 49 characters.

• We guarantee that the graders will enter only integers as their response to the 1st-level menu and only characters as response to the 2nd-level menu.

Sample Run

Here is a link to the sample output of this program.

Submitting the Program

To submit your program, type the following command at the Unix prompt

submit cs201 Proj4 followed by the .c and .h files necessary for compilation

To verify that your project was submitted, you can execute the following command at the Unix prompt. It will show all files that you submitted in a format similar to the Unix 'ls' command.

submitls cs201 Proj4

Wednesday, 16-Apr-2008 15:01:02 EDT