c++字符串学习

#include <iostream>
#include <cstring>
#include <cstdio>
#include <cstdlib>
using namespace std;
int d,t;
char s[100000];
int main()
{
    scanf("%d",&d);
    d=d% 26;
    scanf("%s",s);
    for (int i=0;i<strlen(s);i++)
    {
        t=s[i]+d;
        while (t>'z') t=t-'z'+'a'-1;
        s[i]=t;
    }
    printf("%s",s);
    return 0;
}