蓝桥杯 基础练习 BASIC-12 十六进制转八进制

 1 //十六进制转二进制，二进制转八进制 
 2  
 3 #include <iostream>
 4 #include <map>
 5 using namespace std;
 6 
 7 int main() {
 8     string s;            //输入的十六进制 
 9     string binaryNum;    //二进制数 
10     int n;
11     cin >> n;
12     
13     string str[16] = {"0000", "0001", "0010", "0011", 
14                       "0100", "0101", "0110", "0111", 
15                       "1000", "1001", "1010", "1011", 
16                       "1100", "1101", "1110", "1111"};
17                       
18     map<string, string> m;
19     m["000"] = "0"; m["001"] = "1"; m["010"] = "2"; m["011"] = "3"; 
20     m["100"] = "4"; m["101"] = "5"; m["110"] = "6"; m["111"] = "7";
21     
22     for (int i = 0; i < n; i++) 
23     {
24         cin >> s;                                
25         int len_s = s.length();
26         for(int j = 0; j < len_s; j++) 
27         {
28             if(s[j] > ‘9‘) 
29             {
30                 binaryNum += str[s[j] - ‘A‘ + 10];
31             } 
32             else
33             {
34                 binaryNum += str[s[j] - ‘0‘];
35             }
36         }
37         
38         int len_b = binaryNum.length();            //二进制数的长度 
39         if(len_b % 3 == 1)                         //将二进制的长度转为3的倍数 
40         {
41             binaryNum = "00" + binaryNum;        
42         } 
43         else if(len_b % 3 == 2) 
44         {
45             binaryNum = "0" + binaryNum;
46         }
47         
48         int flag = 0;        //前导为0标志
49         string temp;        //获取三位二进制数，将其转为八进制 
50         string octalNum;    //八进制数 
51         for(int j = 0; j < len_b; j += 3) 
52         {
53             temp = binaryNum.substr(j, 3);
54             octalNum = m[temp];
55             if(j == 0 && octalNum == "0")    //如果取出的二进制数前三位为0，则重新取接下来的3位二进制数 
56             {
57                 flag = 1;
58                 continue;
59             }
60             if(flag == 1 && j == 3 && octalNum == "0") //如果接下来的二进制还为0，则继续取（后边取的肯定不是0） 
61             {
62                 continue;
63             }
64             cout << octalNum;
65         }
66         
67         cout << endl;
68         binaryNum = "";
69     }
70     
71     return 0;
72 }