C++primer 9.6节练习

 1 #include<iostream>
 2 #include<string>
 3 #include<vector>
 4 #include <stack>
 5 
 6 using namespace std;
 7 
 8 //本来是想实现一个计算功能的，可是对于字符串转数值计算方面实在无能为力，等学的多了再回来看看
 9 int main()
10 {
11     string str1{ "(1 + ((2 + 3) * 5))" };
12     bool count = true;
13     stack<char> str;
14     string str2;
15     for (string::size_type it = 0; it != str1.size(); ++it)
16     {
17         if (str1[it] == ‘(‘)
18             count = true;
19         if (str1[it] == ‘)‘)
20             count = false;
21         if (count)
22             str.push(str1[it]);
23         if (!count)
24         {
25             while (str.top() != ‘(‘)
26             {
27                 str2 += str.top();
28                 str.pop();
29             }
30             str.pop();
31             count = true;
32         }
33     }
34     cout << str2 << endl;
35     system("pause");
36     return 0;
37 }