【C/C++】任意進制轉換

　　進制轉換：R進制->10進制；10進制->R進制、

#include<bits/stdc++.h> 
using namespace std;
/*函數：r進制轉換成10進制*/
int rToTen(string n,int r){
    //將r進制轉為10進制，n是該r進制的字符串表示
    int len = n.length();
    int ans = 0;
    int i = 0;
    while(i<len){
        ans*=r;
        ans+=n[i]-'0';
        i++;
    }
    return ans;
}

/*函數：十進制轉任意進制*/ 
string tenToR(int n,int r){
    //十進制n轉r進制 ，返回字符串s 
    char str[1005];
    stack<int>s;
    while(n){
        s.push(n%r);
        n = n/r;
    }
    int i = 0;
    while(!s.empty()){
        switch(s.top()){
            case 10:
                str[i++] = 'A';
                break; 
            case 11:
                str[i++] = 'B';
                break;
            case 12:
                str[i++] = 'C';
                break;
            case 13:
                str[i++] = 'D';
                break;
            case 14:
                str[i++] = 'E';
                break;
            case 15:
                str[i++] = 'F';
                break;
            default:
                str[i++] = s.top()+'0';    
        }
        s.pop();
    }
    string st = str;
    return st;
}


int main(){
    cout<<rToTen("10010",2)<<endl;
    cout<<tenToR(18,2)<<endl;
}