十进制与m进制的相互转化

//十进制转成m进制
#include <bits/stdc++.h>
#define ll long long
#define ull unsigned long long
#define ld long double
#define maxn 20010
using namespace std;
int n,m,l;
char s[10000];
int main()
{
    cin>>n>>m;
    while(n>0)
    {
        if(m>10&&n%m>=10)
        {
            s[l++]=n%m+'A'-10;
        }
        else
        {
            s[l++]=n%m+'0';
        }
        n/=m;
    }
    for(int i=l-1;i>=0;i--)
    {
        cout<<s[i];
    }
    cout<<endl;
    return 0;
}

//m进制转成十进制
#include <bits/stdc++.h>
#define ll long long
#define ull unsigned long long
#define ld long double
#define maxn 20010
using namespace std;
char s[10000],*a;
int m;
int main()
{
    cin>>s>>m;
    cout<<strtol(s,&a,m)<<endl;
    return 0;
}