This assignment is designed for the student to learn about pointers in C++ as well as basic file I/O and cryptography. It will reinforce the concepts of strings, vectors, and functions.

Part A: Pointers

1. Pointer Gymnastics:

We are providing you with 3 files: Pointers.h,

pointer-sandbox.cpp, and manip.h which are available in the Lab 10/Part A folder.

The sandbox file should be complete. If you compile it you will see what the output should be and what it is now. Your goal is to make them the same.

You will be editing the manip.h file and compiling the sandbox file.

You will use the Pointers class implemented in Pointers.h.

Youll note that EVERY sample output calls a manipX function, with X matching the function number. These functions are located in manip.h and are currently empty. Your job is to fill in the manip functions in manip.h so your output would match the sample code!

Writing the manip functions will require you to FULLY understand what the Pointers class does, what private variables it stores, and most importantly what the member functions can do. Study the sample output and try to imagine how to setup your pointers to match the output.. Each manip function is passed parameters which allow it to change a Pointer instance somehow in order for you to get the correct output

DRAW PICTURES of what memory looks like! Each manip function can be filled in with less than or equal to 3 lines of code, with 7 of them requiring only one line. You may use ANY C/C++ tricks you can to get the tests to pass. Your proposed changes will only affect the manip.h. File. Sample Output maninp1: 10 = 10 maninp2:

45 = 45

maninp3: 383 = 383 maninp4:

0x7fff8072b6fc = 0x7fff8072b6fc

1 == 1 maninp5: 45 = 45 maninp6: 10 = 10 maninp7: 15 = 15 maninp8: 199 = 199 maninp9: 0xbe9c20 = 0xbe9c20 maninp10:

199 = 199

1. Simple Linked List:

Modify LList.h to implement the functions or operator overloading listed below. Most of the functions are stubbed out so you just need to add the proper logic.

You will be editing the LList.h file and compiling the sandbox file. Here is a list of the required methods you must fill in:

LList.h

• push_back(int) Place the given value on the end of the linked-list.
• reverse() const Return a new linked-list which is the current one reversed.
• size() Returns the size (length) of the linked-list.
• empty() Return true if the list is empty otherwise return false.
• pop_back() Removes the last element of the linked-list.

If the list is empty do nothing.

• operator==(LList) Return true if the current linked-list contains identical values to the passed one.
• Overload the plus (+) operator to add two lists together.

Extra Credit: 10-Points Each

• getAt(unsigned) Return the value at the given position, or throw a logic error if the index is invalid. See the overloaded [] operator for hints on how to throw an exception.
• setAt(int, unsigned) Assign the given value to the given position (0-based). Throw a logic error if the index is invalid.

You can use list-sandbox.cpp to experiment with the linked-list classes. Compile list-sandbox.cpp to a list-sandbox executable. List-sandbox.cpp will not be graded.

Tip for Testing: Use the list-sandbox.cpp to create linked list objects and also test out your various list modifying functions. LList.h has a definition for overloaded << operator. This member function can let you print out the contents of the list and hence can be a helpful function to test your code in list-sandbox.cpp. Also, size() is called within this function so you will need to implement that one first.

Part B: File I/O & Cryptography

13. Rot13 Encoding/decoding (rot13.cpp)

Objective:

The goal of part B is to create a program to encode files and strings using the rot13 encoding method. Information about the rot13 method can be found at http://www.rot13.com /.

Implement the rot13 algorithm using functions, strings and file I/O. You program should use at least 3 to 4 functions. It should be able to read in a text file from a specified filename, encode using rot13, and write it to a specified file. It should be able to decrypt it in the same way.

Create a rot13.cpp file. You will need to provide the file I/O and the functions that implements the rot13 algorithm. Note: rot13 is very specific version of the Caesar cipher.

The rot13 algorithm just simply rotates each individual alphabetic character by 13 characters. It leaves the numbers, punctuation, etc alone. To encrypt you just rotate each character by 13 characters. To decrypt you just rotate (in either direction) the characters by 13 as well. Please preserve the case of the rotated letter.

You may want to convert all lowercase to uppercase characters before performing math on them to avoid overflows. You will want to convert them back to lowercase when done. Example 1:

Given the letter a the encrypted letter becomes a + 13 = 110 or n

Given encrypted letter n than n + 13 (or 123) is greater than z so it wraps around (in this case back to a).

If using a char data type, the above would overflow and become a negative number. It is suggested that you convert lowercase characters to uppercase before performing the rotation and then convert back to lowercase.

Example 2:

Assuming your input file contains the following text:

The quick brown fox jumps over the moon!

Your encrypted file would be:

Gur dhvpx oebja sbk whzcf bire gur zbba!

Note: The decrypted text should be the same as the original file text.

1. Implement the modified Caesar cipher

Objective:

The goal of part C is to create a program to encode files and strings using the caesar cipher encoding method. Information

about the caesar method can be found at

http://www.braingle.com/brainteasers/codes/caesar.php.

Note: the standard caesar cipher uses an offset of 3. We are going to use a user supplied string to calculate an offset. See below for details on how to calculate this offset from this string.

First create caesar.cpp . You are required to implement this as a set of at least three to four functions. It should be able to read in a specified text file, encode using a modified caesar cipher, and write it to a specified file. It should be able to decrypt it in the same way.

Using the rot13.cpp file as a template just modify the algorithm to receive a string as a key. You will use this key to calculate the rotation count. You rotate in the right direction for encryption and in the left direction for decryption.

The standard caesar cipher uses a 3 character offset for rotation. However, we are going to use an ASCII string (as a key) to determine this offset. See the following examples for details. An example of how to calculate the key:

Given the sample key deF:

First add all the ASCII values: ASCII_SUM = d + e + F =

100 + 101 + 70 = 271

Than calculate the rotation count by using the following equation:

Count equals (ASCII_SUM % 23) + 3 = (271 % 23) + 3 = 21

The plus three in the above equation forces the code to rotate characters by at least three (3) positions. Example:

Key: deF Original file text:

This is a secret ring decoder that I found in a cracker jack box!

Encrypted file text:

Ocdn dn v nzxmzo mdib yzxjyzm ocvo D ajpiy di v xmvxfzm evxf wjs!

Note: The decrypted text should be the same as the original file text.