itsa基 32 字母往後移

#include<iostream>
#include<string>
using namespace std;

int main()
{
int n;
string str;
getline(cin,str);
cin >> n;
for (int i = 0;i < str.length(); i++)
{
if (str[i] >= 'A' && str[i] <= 'Z')
str[i] = (str[i] - 'A' + n) % 26 + 'A';
if (str[i] >= 'a' && str[i] <= 'z')
str[i] = (str[i] - 'a' + n) % 26 + 'a';
if (str[i] >= '0' && str[i] <= '9')
str[i] = (str[i] - '0' + n) % 10 + '0';
}
cout << str << endl;
return 0;
}