基础练习 ——十六进制转十进制

 1 #include<iostream>
 2 #include<string>
 3 #include<cmath>
 4 using namespace std;
 5 int main()
 6 {
 7     string str;
 8     while(cin >> str)
 9     {
10         int len = str.length();
11         long long int res = 0;
12         int t = len;
13         for(int i = 0;i < len;i++)
14         {
15             if(isdigit(str[i]))
16             {
17                 res = res + (str[i] - ‘0‘) * pow(16,t-1);
18                 t--;
19             }
20             else
21             {
22                 res = res + (str[i] - ‘A‘ + 10) * pow(16,t-1);
23                 t--;
24             }
25         }
26         cout << res << endl;
27     }
28     return 0;
29 }