Ascii код символа при дешифровании на еденицу меньше чем должен быть

#include <iostream>
#include <stdlib.h>
 
 
using namespace std;
 
int main() {
 
setlocale(LC_ALL, "Russian");
 
int key = 0;
char choise;
string text;
string code;
 
cout << "Input string to encrypt: ";
getline(cin,text);
 
cout << "\nYou have entered: " << text << endl;
cout << "Input key to encrypt: ";
cin >> key;
if(key > 255)
    key = key % 255;
 
cout << "Encrypting..." << endl;
 
for(int i=0; i<text.length(); i++) {
    code[i] = char(((int)text[i] + key) % 255);
    code += code[i]; 
}
 
cout << "Enctypted code is: " << code << endl;
 
cout << "Do you want to decrypt?(y,n)" << endl;
cin >> choise;
if(choise == 'n')
    exit(0);
cout << "Dectyption..." << endl;
text = "";
 
for(int i=0; i<code.length(); i++) {
    text[i] = char((int(code[i]) - key + 255) % 255);
    text += text[i];
}
 
cout << "Decrypted text is: " <<  text << endl;
 
return 0;
}

code[i] = char(((int)text[i] + key) % 255);

#include <iostream>
#include <stdlib.h>
#include <string>
 
using namespace std;
 
int main() {
 
setlocale(LC_ALL, "Russian");
 
int key = 0;
char choise;
string text;
wstring code;
 
cout << "Input string to encrypt: ";
getline(cin,text);
 
cout << "\nYou have entered: " << text << endl;
cout << "Input key to encrypt: ";
cin >> key;
if(key > 255)
    key = key % 255;
 
cout << "Encrypting..." << endl;
 
for(int i=0; i<text.length(); i++) {
    code.push_back(char(((int)text[i] + key) % 255));
    //code += code[i]; 
}
 
wcout << "Enctypted code is: " << code;
cout << endl;
 
cout << "Do you want to decrypt?(y,n)" << endl;
cin >> choise;
if(choise == 'n')
    exit(0);
cout << "Dectyption..." << endl;
text.clear();
 
for(int i=0; i<code.length(); i++) {
    text.push_back(char((int(code[i]) - key + 255) % 255));
    //text += text[i];
}
 
cout << "Decrypted text is: " <<  text << endl;
 
return 0;
}