Vigneer

#include <iostream>
#include <string>

using namespace std;

string wordUP(string &k) {
    string kk;
    for (int i = 0; i < k.size(); ++i) {
        if (k[i] == ' ') {
            kk += ' ';
            continue;
        }
        if (k[i] >= 'A' && k[i] <= 'Z')
            kk += k[i];
        else if (k[i] >= 'a' && k[i] <= 'z')
            kk += k[i] + 'A' - 'a';
    }
    return kk;
}

string shifr(string t, string k) {
    string output;
    for (int i = 0, j = 0; i < t.length(); ++i) {
        char chr = t[i];
        if (chr == ' ') {
            output += ' ';
            continue;
        }
        output += (chr + k[j] - 2 * 'A') % 26 + 'A';
        j = (j + 1) % k.length();
    }
    return output;
}

string decshift(string t, string k) { // аналогично шифрованию, только обратное
    string output;
    for (int i = 0, j = 0; i < t.length(); ++i) {
        char chr = t[i];
        if (chr == ' ') {
            output += ' ';
            continue;
        }
        output += (chr - k[j] + 26) % 26 + 'A';
        j = (j + 1) % k.length();
    }
    return output;
}


int main() {
    string key, str;
    cout << "pls, enter str to encrypt:\n";
    getline(cin, str);
    cout << "pls, enter key:\n";
    getline(cin, key);
    str = wordUP(str);

    string new_key = wordUP(key);
    string encrypted = shifr(str, new_key);
    string decrypt = decshift(encrypted, new_key);

    cout << "Original Message: " << str << endl;
    cout << "Encrypted Message: " << encrypted << endl;
    cout << "Decrypted Message: " << decrypt << endl;
}