Caesar Cipher Gaming Project in C++

#include <iostream>
#include <string>

using namespace std;

// Function to encrypt a message using Caesar cipher
string encrypt(string plaintext, int shift) {
    string ciphertext = "";
    for (char c : plaintext) {
        if (isalpha(c)) { // Check if the character is a letter
            char base = islower(c) ? 'a' : 'A';
            char encryptedChar = (c - base + shift) % 26 + base;
            ciphertext += encryptedChar;
        } else {
            ciphertext += c; // Non-alphabetic characters remain unchanged
        }
    }
    return ciphertext;
}

// Function to decrypt a message using Caesar cipher
string decrypt(string ciphertext, int shift) {
    return encrypt(ciphertext, 26 - shift); // Decryption is just encryption with the inverse shift
}

int main() {
    string text;
    int shift;

    // Input plaintext and shift value
    cout << "Enter the text: ";
    getline(cin, text);
    cout << "Enter shift value (1-25): ";
    cin >> shift;

    // Validate shift value
    if (shift < 1 || shift > 25) {
        cerr << "Error: Shift value must be between 1 and 25." << endl;
        return 1;
    }

    // Encrypt the text
    string encryptedText = encrypt(text, shift);
    cout << "Encrypted text: " << encryptedText << endl;

    // Decrypt the text
    string decryptedText = decrypt(encryptedText, shift);
    cout << "Decrypted text: " << decryptedText << endl;

    return 0;
}

#include <iostream>

#include <string>

using namespace std;

// Function to encrypt a message using Caesar cipher

string encrypt(string plaintext, int shift) {

string ciphertext = "";

for (char c : plaintext) {

if (isalpha(c)) { // Check if the character is a letter

char base = islower(c) ? 'a' : 'A';

char encryptedChar = (c - base + shift) % 26 + base;

ciphertext += encryptedChar;

} else {

ciphertext += c; // Non-alphabetic characters remain unchanged

}

return ciphertext;

}

// Function to decrypt a message using Caesar cipher

string decrypt(string ciphertext, int shift) {

return encrypt(ciphertext, 26 - shift); // Decryption is just encryption with the inverse shift

}

int main() {

string text;

int shift;

// Input plaintext and shift value

cout << "Enter the text: ";

getline(cin, text);

cout << "Enter shift value (1-25): ";

cin >> shift;

// Validate shift value

if (shift < 1 || shift > 25) {

cerr << "Error: Shift value must be between 1 and 25." << endl;

return 1;

}

// Encrypt the text

string encryptedText = encrypt(text, shift);

cout << "Encrypted text: " << encryptedText << endl;

// Decrypt the text

string decryptedText = decrypt(encryptedText, shift);

cout << "Decrypted text: " << decryptedText << endl;

return 0;

}

Explanation

Include Libraries:
- #include <iostream>: For input and output operations.
- #include <string>: For using std::string.
Encrypt Function:
- string encrypt(string plaintext, int shift): Encrypts the plaintext using the Caesar cipher.
  - plaintext: The input string to be encrypted.
  - shift: The number of positions each letter in the plaintext is shifted.
  - Iterates over each character in plaintext:
    - Checks if the character is a letter (isalpha(c)).
    - Determines if it is uppercase or lowercase to set the base ('A' or 'a').
    - Applies the shift using modular arithmetic to ensure the result wraps around the alphabet.
    - Appends the encrypted character to ciphertext.
    - Non-alphabetic characters are added to ciphertext unchanged.
Decrypt Function:
- string decrypt(string ciphertext, int shift): Decrypts the ciphertext by using the inverse shift.
  - Calls the encrypt function with 26 - shift, as decryption in Caesar cipher is essentially shifting backwards by the same amount.
Main Function (main):
- Prompts the user to enter text and shift value.
- Validates that the shift value is between 1 and 25.
- Encrypts the input text using the encrypt function and prints the result.
- Decrypts the encrypted text using the decrypt function and prints the result.

Notes:

Shift Value: The Caesar cipher typically uses a shift between 1 and 25 to avoid trivial cases where the shift is 0 or 26, which would not change the text.
Modular Arithmetic: Ensures that the shift wraps around the alphabet correctly.
Non-Alphabetic Characters: Are not altered by the cipher and are included as-is in the output.

Caesar Cipher Gaming Project in C++

Explanation

Notes:

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