Caesar Crypher/Decypher Program. C++ [closed] - c++

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I'm working on a school project, my project is a Cypher and Decypher program that works with Caesar Algorithm.
My program has to have the following characteristics:
The program must give the user the option to initiate again. (Done.)
If the user inputs something wrong, the program must ask the user to imput again. (Done with a bug.)
The user can only input letters and - por spaces. (I only need to add the space thing.)
The letter must be moved 5 places (ie. A = F) (Done.)
The program must consider capital letters. (Done.)
Each time you input a letter the screen must clear. (Done.)
At the end of the program you must be able to see the encrypted or decrypted text. (Needs to finish.)
What I need to know is how to make the program show me the encrypted text, counting all the inputs I have made so far while the program has been running.
And an extra thing is how can I input a whole text sentence and apply the Caesar Encryption, obviously I'd have to change almost all my code but I'd like how to do it.
This is the code I have so far, sorry if the sentences are in Spanish but I am living in Mexico for the moment and my classes are in Spanish. If you need me to translate the text I can gladly do it for you.
#include <iostream>
#include <stdlib.h>
#include <time.h>
using namespace std;
int main(int, char**) {
// Variables.
char l;
int x = 0;
char y = x + l;
bool volverainiciar;
volverainiciar = 1;
while (volverainiciar == 1) {
cout << "Favor de introducir la letra del mensaje que desea codificar."
<< endl;
cin >> l;
cout << " " << endl;
cout << " " << endl;
if ((l >= 'a' && l <= 'u') || (l >= 'A' && l <= 'U')) {
cout << "El mensaje a codificar es: " << l;
cout << " " << endl;
cout << " " << endl;
cout << "La letra " << l << " tiene un codigo ASCII de: " << x + l
<< endl;
y = (l + 5);
cout << "La letra " << l << " encriptado tiene un valor de: " << y
<< endl;
cout << " " << endl;
cout << " " << endl;
cout << "Se limpiara la pantalla..." << endl;
system("pause");
system("cls");
cout << " Desea volver a iniciar?" << endl;
cout << " " << endl;
cout << " Para volver a iniciar (1) , para no volver a "
"iniciar (0)" << endl;
cout << " " << endl;
cout << "Volver a iniciar: ";
cin >> volverainiciar;
cout << " " << endl;
cout << " " << endl;
} else if ((l >= 'v' && l <= 'z') || (l >= 'V' && l <= 'Z')) {
switch (l) {
case 'v':
cout << "El mensaje a codificar es: " << l;
cout << " " << endl;
cout << " " << endl;
cout << "La letra u tiene un codigo ASCII de: " << x + l
<< endl;
cout << "La letra " << l
<< " encriptado tiene un valor de: a" << endl;
cout << " " << endl;
cout << " " << endl;
cout << "Se limpiara la pantalla..." << endl;
system("pause");
system("cls");
cout << " Desea volver a iniciar?" << endl;
cout << " " << endl;
cout << " Para volver a iniciar (1) , para no volver "
"a iniciar (0)" << endl;
cout << " " << endl;
cout << "Volver a iniciar: ";
cin >> volverainiciar;
cout << " " << endl;
cout << " " << endl;
break;
case 'w':
cout << "El mensaje a codificar es: " << l;
cout << " " << endl;
cout << " " << endl;
cout << "La letra u tiene un codigo ASCII de: " << x + l
<< endl;
cout << "La letra " << l
<< " encriptado tiene un valor de: b" << endl;
cout << " " << endl;
cout << " " << endl;
cout << "Se limpiara la pantalla..." << endl;
system("pause");
system("cls");
cout << " Desea volver a iniciar?" << endl;
cout << " " << endl;
cout << " Para volver a iniciar (1) , para no volver "
"a iniciar (0)" << endl;
cout << " " << endl;
cout << "Volver a iniciar: ";
cin >> volverainiciar;
cout << " " << endl;
cout << " " << endl;
break;
case 'x':
cout << "El mensaje a codificar es: " << l;
cout << " " << endl;
cout << " " << endl;
cout << "La letra u tiene un codigo ASCII de: " << x + l
<< endl;
cout << "La letra " << l
<< " encriptado tiene un valor de: c" << endl;
cout << " " << endl;
cout << " " << endl;
cout << "Se limpiara la pantalla..." << endl;
system("pause");
system("cls");
cout << " Desea volver a iniciar?" << endl;
cout << " " << endl;
cout << " Para volver a iniciar (1) , para no volver "
"a iniciar (0)" << endl;
cout << " " << endl;
cout << "Volver a iniciar: ";
cin >> volverainiciar;
cout << " " << endl;
cout << " " << endl;
break;
case 'y':
cout << "El mensaje a codificar es: " << l;
cout << " " << endl;
cout << " " << endl;
cout << "La letra u tiene un codigo ASCII de: " << x + l
<< endl;
cout << "La letra " << l
<< " encriptado tiene un valor de: d" << endl;
cout << " " << endl;
cout << " " << endl;
cout << "Se limpiara la pantalla..." << endl;
system("pause");
system("cls");
cout << " Desea volver a iniciar?" << endl;
cout << " " << endl;
cout << " Para volver a iniciar (1) , para no volver "
"a iniciar (0)" << endl;
cout << " " << endl;
cout << "Volver a iniciar: ";
cin >> volverainiciar;
cout << " " << endl;
cout << " " << endl;
break;
case 'z':
cout << "El mensaje a codificar es: " << l;
cout << " " << endl;
cout << " " << endl;
cout << "La letra u tiene un codigo ASCII de: " << x + l
<< endl;
cout << "La letra " << l
<< " encriptado tiene un valor de: e" << endl;
cout << " " << endl;
cout << " " << endl;
cout << "Se limpiara la pantalla..." << endl;
system("pause");
system("cls");
cout << " Desea volver a iniciar?" << endl;
cout << " " << endl;
cout << " Para volver a iniciar (1) , para no volver "
"a iniciar (0)" << endl;
cout << " " << endl;
cout << "Volver a iniciar: ";
cin >> volverainiciar;
cout << " " << endl;
cout << " " << endl;
break;
case 'V':
cout << "El mensaje a codificar es: " << l;
cout << " " << endl;
cout << " " << endl;
cout << "La letra u tiene un codigo ASCII de: " << x + l
<< endl;
cout << "La letra " << l
<< " encriptado tiene un valor de: A" << endl;
cout << " " << endl;
cout << " " << endl;
cout << "Se limpiara la pantalla..." << endl;
system("pause");
system("cls");
cout << " Desea volver a iniciar?" << endl;
cout << " " << endl;
cout << " Para volver a iniciar (1) , para no volver "
"a iniciar (0)" << endl;
cout << " " << endl;
cout << "Volver a iniciar: ";
cin >> volverainiciar;
cout << " " << endl;
cout << " " << endl;
break;
case 'W':
cout << "El mensaje a codificar es: " << l;
cout << " " << endl;
cout << " " << endl;
cout << "La letra u tiene un codigo ASCII de: " << x + l
<< endl;
cout << "La letra " << l
<< " encriptado tiene un valor de: B" << endl;
cout << " " << endl;
cout << " " << endl;
cout << "Se limpiara la pantalla..." << endl;
system("pause");
system("cls");
cout << " Desea volver a iniciar?" << endl;
cout << " " << endl;
cout << " Para volver a iniciar (1) , para no volver "
"a iniciar (0)" << endl;
cout << " " << endl;
cout << "Volver a iniciar: ";
cin >> volverainiciar;
cout << " " << endl;
cout << " " << endl;
break;
case 'X':
cout << "El mensaje a codificar es: " << l;
cout << " " << endl;
cout << " " << endl;
cout << "La letra u tiene un codigo ASCII de: " << x + l
<< endl;
cout << "La letra " << l
<< " encriptado tiene un valor de: C" << endl;
cout << " " << endl;
cout << " " << endl;
cout << "Se limpiara la pantalla..." << endl;
system("pause");
system("cls");
cout << " Desea volver a iniciar?" << endl;
cout << " " << endl;
cout << " Para volver a iniciar (1) , para no volver "
"a iniciar (0)" << endl;
cout << " " << endl;
cout << "Volver a iniciar: ";
cin >> volverainiciar;
cout << " " << endl;
cout << " " << endl;
break;
case 'Y':
cout << "El mensaje a codificar es: " << l;
cout << " " << endl;
cout << " " << endl;
cout << "La letra u tiene un codigo ASCII de: " << x + l
<< endl;
cout << "La letra " << l
<< " encriptado tiene un valor de: D" << endl;
cout << " " << endl;
cout << " " << endl;
cout << "Se limpiara la pantalla..." << endl;
system("pause");
system("cls");
cout << " Desea volver a iniciar?" << endl;
cout << " " << endl;
cout << " Para volver a iniciar (1) , para no volver "
"a iniciar (0)" << endl;
cout << " " << endl;
cout << "Volver a iniciar: ";
cin >> volverainiciar;
cout << " " << endl;
cout << " " << endl;
break;
case 'Z':
cout << "El mensaje a codificar es: " << l;
cout << " " << endl;
cout << " " << endl;
cout << "La letra u tiene un codigo ASCII de: " << x + l
<< endl;
cout << "La letra " << l
<< " encriptado tiene un valor de: E" << endl;
cout << " " << endl;
cout << " " << endl;
cout << "Se limpiara la pantalla..." << endl;
system("pause");
system("cls");
cout << " Desea volver a iniciar?" << endl;
cout << " " << endl;
cout << " Para volver a iniciar (1) , para no volver "
"a iniciar (0)" << endl;
cout << " " << endl;
cout << "Volver a iniciar: ";
cin >> volverainiciar;
cout << " " << endl;
cout << " " << endl;
break;
}
} else {
cout << "Ese simbolo no es valido, favor de introducir uno valido."
<< endl;
cin >> l;
cout << " " << endl;
cout << " " << endl;
continue;
}
}
cout << "Gracias por usar el encriptador/desencriptador." << endl;
exit;
return 0;
}
If you have any suggestions I'll gladly read them too :)
And sorry for any misspellings my english is not perfect because almost my whole life I've been living here...

Answer 1

I hate to trash your really long program, but it was annoying.
Try this:
// Given the input character is in x.
if (std::isalpha(x))
{
if (std::islower(x))
{
y = (x - 'a'); // Convert to a number.
y = y + 5; // Left shift by 5
y = y % 26; // Modulo arithmetic for all letters in alphabet
y = y + 'a'; // Convert back to character.
}
else
{
y = (x - 'A'); // Convert to a number.
y = y + 5; // Left shift by 5
y = y % 26; // Modulo arithmetic for all letters in alphabet
y = y + 'A'; // Convert back to character.
}
}
One of my pet peeves is duplicate code. Although there is duplicate code above, I've reduced the amount of duplication in your code. Feel free to add all your cout statements in the code above.
By the way, you can "block write" your data to cout, if the data doesn't use variables.
Example:
static const char answer_text[] =
"\n"
"\n"
"La letra u tiene un codigo ASCII de: ";
//...
cout.write(answer_text, sizeof(answer_text) - 1);
This will allow you to use the cout.write statement everywhere you need to use the same text. Less typing, less lines, less probability of injecting a defect.