Assignment $4$

CS$2340$ Fall $2024$

Palindromes

A palindrome is a word or phrase that reads the same from left to right as right to left.$$ A simple palindrome is $$kayak$,$ for example.$$ Other rules are that you ignore punctuation and letter case.$$ For example, $$Madam$,$ I$$m Adam$$ is a palindrome despite commas, spaces, and upper and lower case differences.$$ Palindromes can also contain digits, such as $12421.$

Write a program that does the following:

$1.$ Request a string from the user.$$ If it is zero length $($the first character is $$

$)$ exit the program.

$2.$ Determine if the string is a palindrome.$$ If so$,$ print $$Palindrome$.$ If not, print $$Not a palindrome.$$

$3.$ Return to request another string.

Program structure:

$1.$ You can assume no input string is longer than $200$ characters.

$2.$ Write a helper function that calls three functions, as defined below. This structure is required.$$ The parameter is the address of the input string in $a$0.$

a$.$ Within this function, you must call another function that removes anything that isn$$t a letter or a number.

b$.$ Within the second function, call a third function that converts lower case to upper case so your comparisons work properly.

c$.$ You must write a function that determines whether the string is a palindrome.$$ Call this with the address of the string in $a$0$ and no other parameters.$$ This function must be recursive.$$ That is$,$ it must test whether the initial string might be a palindrome and return true if it the outer two characters match and false if they don$$t$,$ meaning if you return false at any level, stop the recursive calls and return false.$$ If you return true, remove the first and last characters of the string and pass the address of the shortened string in $a$0.$ Treat the original string as immutable, much as Java does. $($How does Java deal with this?$)$

$3.$ You must have two files.$$ The first has the main body of your code that requests a string, calls a function that checks a palindrome, which is item $2,$ above plus initialization code.$$ The second file has any subroutines you may need, such as removing punctuation and converting case.

This structure is part of the requirements and something you need to learn.$$

Recursion is also part of this.$$ Consider how you pass a string as an argument such that each level gets a new string on the stack.

Is a string of length $0$ or length $1$ a palindrome?$$ This is your base case.

I suggest you return the Boolean result as $1$ for true and zero for false in $v$0.$

You will need to check the $$Assemble all files in directory$$ setting for this to work.

Your program will be tested with a string that contains no letters and no digits.

To hand in through eLearning: A Zip file named CS$2340-$Asg$4-.$zip$$ where you replace with your netID.$$ For example, if I were to hand it in$,$ the name would be CS$2340-$Asg$4-$jxc$064000.$zip.$$ This must contain ALL files necessary to assemble and run your program.

Grading Criteria

Comments and variable names

$15$

Recognizes correct palindromes and rejects things that are not

$35$

Correct program structure

$40$

Does not crash

$10$

Total

$100$

Additional grading criteria:

Errors in detecting and recognizing correct and incorrect palindromes: $-5$ to $-35,$ depending upon severity.

Crashes for any reason: $-10$ or more

Only one file: $-25$

Poor code formatting: $-2$ to $-10$

Poor coding practices, such as spaghetti code, use of magic numbers, etc. $-2$ to $-10$

Using $.$include for your secondary file. $-25$

Code structure such as calls not nested, not using the stack, not using it correctly, in$-$line code for the palindrome, etc. $-5$ to $-35$

Exits after every test. $-5$

Does not exit when I press enter. $-5$

Not recursive. $-35$ or more, depending upon severity.

Zip file does not contain your NetID. $-5$

Missing header comments or other documentation problems: $-2$ to $-15.$

Does not assemble. $-70$ or more, depending upon severity.