基础练习 十六进制转八进制

 1 #include <iostream>
 2 #include <string>
 3 
 4 using namespace std;
 5 
 6 string HexToBin(string s)  //16进制转2进制
 7 {
 8     string str = "";
 9     for (int i = 0; i < s.size(); ++i)
10     {
11         switch (s[i])
12         {
13         case ‘0‘: str += "0000"; break;
14         case ‘1‘: str += "0001"; break;
15         case ‘2‘: str += "0010"; break;
16         case ‘3‘: str += "0011"; break;
17         case ‘4‘: str += "0100"; break;
18         case ‘5‘: str += "0101"; break;
19         case ‘6‘: str += "0110"; break;
20         case ‘7‘: str += "0111"; break;
21         case ‘8‘: str += "1000"; break;
22         case ‘9‘: str += "1001"; break;
23         case ‘A‘: str += "1010"; break;
24         case ‘B‘: str += "1011"; break;
25         case ‘C‘: str += "1100"; break;
26         case ‘D‘: str += "1101"; break;
27         case ‘E‘: str += "1110"; break;
28         case ‘F‘: str += "1111"; break;
29         }
30 
31     }
32     return str;
33 }
34 
35 
36 
37 int main()
38 {
39     
40     int n;
41     while (cin >> n)
42     {
43         string s;
44         for (int i = 0; i < n; ++i)
45         {
46             cin >> s;
47             string binStr = HexToBin(s);  //先将s转换为二进制串binStr
48             int a = (int)binStr.size() % 3;
49             if (a != 0)        //如果二进制串的长度不是3的倍数,就在前面补零
50             {
51                 for (int i = 1; i <= 3 - a; ++i)
52                     binStr = "0" + binStr;
53             }
54 
55             for (int i = 0; i < binStr.size(); i += 3)
56             {
57                 string str;
58                 str = binStr.substr(i, 3);    //截取binStr长度为3的子串
59                 if (str == "000" && i != 0)
60                     cout << 0;
61                 else if (str == "001")
62                     cout << 1;
63                 else if (str == "010")
64                     cout << 2;
65                 else if (str == "011")
66                     cout << 3;
67                 else if (str == "100")
68                     cout << 4;
69                 else if (str == "101")
70                     cout << 5;
71                 else if (str == "110")
72                     cout << 6;
73                 else if (str == "111")
74                     cout << 7;
75             }
76             cout << endl;
77         }
78         
79     }
80 
81     return 0;
82     
83 }