Convert between any hex

k-ary rotation band 10

#include <bits/stdc++.h>
using namespace std;
int main()
{
    string s;
    int sum=0,k;
    cin>>s>>k;
    for(int i=0;i<s.size();++i){
        sum*=k;
        if(s[i]=='A'||s[i]=='B'||s[i]=='C'||s[i]=='D'||s[i]=='E'||s[i]=='F'){
            sum+=(s[i]-'A'+10);
        }
        else{
            sum+=(s[i]-'0');
        }
    }
    cout <<sum << endl;
    return 0;
}

Reprinted from https://blog.csdn.net/qq_41785863/article/details/84101711