进制转换

#include <bits/stdc++.h>
using namespace std;
string s="0123456789ABCDEF";
int main()
{
    int n,r;
    while(cin>>n>>r)
    {
        string c;
        if(!n)cout<<"0\n";
        else
        {
            if(n<0)cout<<"-",n=-n;
            while(n)c+=s[n%r],n/=r;
            reverse(c.begin(),c.end());
            cout<<c<<"\n";
        }
    }
    return 0;
}

#include <bits/stdc++.h>
using namespace std;

int main()
{
    string s;
    //读入要进行转换的字符串s
    cin>>s;
    //设置变量t去保存这个答案
 　　int t=0;
    for(int i=0;s[i];i++)
    {
        t=t*2+(s[i]-‘0‘);
    }
    cout<<t<<"\n";
}