encryption

#include <iostream>
#include <fstream>

using namespace std;

const string in_alphabet = "абвгдеёжзийклмнопрстуфхцчшщъыьэюя ";
//const string out_alphabet = "qazwsxedcrfvtgbyhnujmik,ol.p;/[']@";
const string out_alphabet = "еёжзийклабвгдмнопрстуфхцчшщъыьэюя ";
const string  key ="бревно";

string read_file(){
    char name_file[255]="s_text.txt";
    cout<<"Введите название файла:";
    //cin>>name_file;
    cout<< name_file<<endl;
    ifstream in (name_file);
    string text;
    in >> text;
    in.close();
    return text;
}

void encryption(){
    string in_text = read_file();
    string out_text;
    string key_re;
    int len_key = key.length();
    int len_alp = in_alphabet.length();
    for(int i = len_key; i<len_alp; i++){
        key_re = key_re+key_re[i%len_key];
    }
    int len_text = in_text.length();
    int x_i, k_i,j;
    ofstream out ("encryption_text.txt");
    for(int i=0; i< len_text; i++){
        x_i = in_alphabet.find(in_text[i]);
        k_i = in_alphabet.find(key_re[i]);
        j = (x_i+k_i)%len_alp;
        out_text[i] = out_alphabet[j];
        cout<<out_text[i];
        out << out_text[i];
    }
    out.close();
}

void decryption(){
    string in_text = read_file();
    string out_text;
    int len_alp = out_alphabet.length();
    string key_valid= "бревно";
    /*cout<<"Введите пароль: ";
    cin>> key_valid;
    cout<<endl;
    cout<<key_valid;*/
    int len_key = key_valid.length();
    /*if(key_valid != key)
    {
       for(int i = len_key; i<len_alp; i++){
            key_valid = key_valid+key_valid[i%len_key];
        }
        cout<< key_valid;
        int len_text = in_text.length();
        int x_i, k_i,j;
        ofstream out ("decryption_text.txt");
        out<< "Text";
        out.close();
    }
    else
    {*/
      for(int i = len_key; i<len_alp; i++){
            key_valid = key_valid+key_valid[i%len_key];
        }
        cout<<key<<endl;
        int len_text = in_text.length();
        int x_i, k_i,j;
        ofstream out ("decryption_text.txt");
        for(int i=0; i< len_text; i++){
            x_i = out_alphabet.find(in_text[i]);
            k_i = in_alphabet.find(key_valid[i]);
            cout<<"x:"<<x_i<<"k:"<<k_i<<endl;
            j = (x_i-k_i+len_alp)%len_alp;
            cout<<j<<endl;
            out_text[i] = in_alphabet[j];
            cout<<out_text[i];
            out << out_text[i];
        }
        out.close();
    //}
}

int main()
{
    setlocale(LC_ALL, "Russian");
    int input;
    loop:;
    cout<<"Выберете режим работы программы"<<endl;
    cout<<"Шифрование [1]"<<endl;
    cout<<"Расшифровка [2]"<<endl;
    cin>>input;
    switch (input){
        case 1: encryption(); break;
        case 2: decryption(); break;
        default: goto loop; break;
    }
    return 0;
}