#include #include #include using namespace std; //for cin and cout and string /** * The ROT13 is a simple encryption mechanism that literally means * rotate by 13 characters (spaces and special chars ignored) * * Author: Ace * Bugs: None Known */ string rot13(string strPhrase) { char cLetter; for (int i=0; i < (int)strPhrase.length(); i++) { cLetter = strPhrase[i]; //Checking capital letters first, ensuring we arent at a space if ('A' <= cLetter && cLetter <= 'Z') { if ('Z' - cLetter >= 13) cLetter += 13; else cLetter = 'A' + 12 - ('Z' - cLetter); //for ensuring only letters are counted. } else if ('a' <= cLetter && cLetter <= 'z') { if ('z' - cLetter >= 13) cLetter += 13; else cLetter = 'a' + 12 - ('z' - cLetter); } strPhrase[i]= cLetter; } return strPhrase; } //the driver int main() { string strPhrase = ""; string strDefault = "Hello world"; //default is for bad and no input cout << "Enter phrase: "; cin >> strPhrase; cout << endl; if(cin.fail()) { strPhrase = strDefault; } if(strPhrase.empty()) strPhrase = strDefault; //checking if only valid chars in the string for(int i = 0; i < (int) strPhrase.size(); i++) { if(!isalpha(strPhrase[i])) { strPhrase = strDefault; break; } } string convert = rot13(strPhrase); cout << "ROT13 Encryption: " << convert << endl; cout << "Decrypted message: " << rot13(convert) << endl; return 0; }