Reference no: EM132335752
Question
This is C++ course. Can someone please help me for this assignment? I'm not sure that my code is right or wrong.
If is wrong can you tell me where did I wrong? Could someone please explain to me this assignment step by step? I really want to understand what teacher want me to write code.
For all assignments in CIS 22B, use heading comments at the top with the following format:
Cryptography - the science of secret writing - is an old science; the first recorded use was well before
1900 B.C. An Egyptian writer used previously unknown hieroglyphs in an inscription.
We will use a simple substitution cypher called rot13 to encode and decode our secret messages.
ROT13 ("rotate by 13 places", sometimes hyphenated ROT-13) is a simple letter substitution cipher that replaces a letter with the 13th letter after it, in the alphabet. ROT13 is a special case of the Caesar cipher which was developed in ancient Rome.
Decryption Key
A|B|C|D|E|F|G|H|I|J|K|L|M
-------------------------
N|O|P|Q|R|S|T|U|V|W|X|Y|Z
(letter above equals below, and vice versa)
As you can see, A becomes N, B becomes O and so on.
Your job is to write a program, with at least four functions, including main, which must do the following:
1. Ask user whether they want to encode or decode a message - if no, then terminate
2. Take the input string from the user, store it in dynamic memory (use new)
3. As appropriate, encode or decode the message using Rot13.
4. Output the encoded/decoded message
5. Delete the input string from dynamic memory (use delete)
Input will be a string of no more than 25 characters.
Blanks get replaced with blanks.
Do not worry about punctuation; there will be no punctuation in the string.
ALPHABET becomes NYCUNORG
Test your program with the following strings:
TAF VF
paddrpf
I'll be using other strings to test your code.
This is the code that I write but not sure it is correct or not
#include <iostream>
#include <string>
using namespace std;
string rot13 (string input);
int main() {
string plaintext;
string cypher;
cout << "input:";
getline(cin,plaintext);
cypher = rot13 (plaintext);
cout << cypher << endl;
plaintext = rot13(cypher);
cout << plaintext << endl;
return 0;
}
string rot13 (string input)
{
int inputSize = input.size();
int index = 0;
while (index != inputSize)
{
if (input [index] >= 97 && input [index] <=109)
input [index] = input [index] + 13;
else if (input[index] >= 110 && input [index] <= 122)
input [index] = input [index] - 13;
else if (input[index]>= 65 && input [index] <= 77)
input [index] = input [index] + 13;
else if (input [index]>= 78 && input [index] <= 90)
input [index] = input [index] - 13;
index++;
}
return input;
}