Character Array Shift (c++)

#include <iostream>
using namespace std;

int main(void){
        char input[] ="12345678";
        int length =(sizeof(input)-1);
        int shift;
        cin>>shift;
        shift = shift % length;
        char *tmp = new char[length];
        for(int i=0; i< length; i++)
                tmp[i]= input[(i+shift)%length];
        cout<< tmp <<endl;
        return 0;
}