C++——不存在从 "std::pair<int, int>" 到 "int" 的适当转换函数

 1 #include <iostream>
 2 #include <vector>
 3 #include <map>
 4 #include <string>
 5 #include <utility>
 6 
 7 
 8 int Update(std::pair<int, int>a) {
 9     std::pair<int, int> temp;
10 
11     std::vector<int> key_row_1(10);
12     std::vector<int> counts_row_1(10);
13 
14     std::vector<int> key_row_2(10);
15     std::vector<int> counts_row_2(10);
16 
17     std::map<int, int>res_row_1;
18     std::map<int, int>res_row_2;
19     std::map<int, std::map<int,int>>res_sum;
20     std::map<int, int>res;
21 
22 
23     int index1 = (a.first % 2);
24     if(counts_row_1[index1]==0) {
25         key_row_1.insert(key_row_1.begin() + index1, a.first);
26         counts_row_1.insert(counts_row_1.begin() + index1, a.second);
27     } else {
28         temp.first = key_row_1[index1];
29         temp.second = counts_row_1[index1];
30         key_row_1.insert(key_row_1.begin() + index1, a.first);
31         counts_row_1.insert(counts_row_1.begin() + index1, a.second);        
32     }
33 
34 
35 
36     if(temp.second != 0) {
37         int index2 = (temp.first % 2);
38         if(counts_row_2[index2]==0) {
39             key_row_2.insert(key_row_2.begin() + index2, temp.first);
40             counts_row_2.insert(key_row_2.begin() + index2, temp.second);
41         } else {
42             if(temp.second > counts_row_2[index2]) {
43                 key_row_2.insert(key_row_2.begin() + index2, temp.first);
44                 counts_row_2.insert(key_row_2.begin() + index2, temp.second);            
45             } 
46         }
47     }
48 
49     
50     std::cout << "stage1" << std::endl;
51     for(int i=0; i<2; i++) {
52         std::cout << "(" << key_row_1[i] << "," << counts_row_1[i] << ")" << "; ";
53         res_row_1.insert(std::pair<int,int>(key_row_1[i], counts_row_1[i]));
54     }
55     std::cout << std::endl;
56     std::cout << "stage2" << std::endl;
57     for(int i=0; i<2; i++) {
58         std::cout << "(" << key_row_2[i] << "," << counts_row_2[i] << ")" << "; ";
59         res_row_2.insert(std::pair<int,int>(key_row_1[i], counts_row_1[i]));
60     }
61     std::cout << std::endl;
62 
63     
64     std::cout << "the final result as follow: " << std::endl;
65 
66     res_sum.insert({1,res_row_1});
67     res_sum.insert({2,res_row_2});
68 
69     auto iter = res_sum.begin();
70     for(; iter != res_sum.end(); ++iter) {
71         res.insert(iter->second.begin(), iter->second.end());
72     }
73 
74     for(const auto &i : res) {
75         std::cout << i.first << ":" << i.second << "; ";
76     }
77     std::cout << '\n';
78 
79 }
80 
81 
82 int main(int argc, char* agrv[]) {
83     std::vector<std::pair<int, int> >p;
84     p.push_back(std::make_pair(1,5));
85     p.push_back(std::make_pair(2,6));
86     p.push_back(std::make_pair(3,7));
87     p.push_back(std::make_pair(4,8));
88     p.push_back(std::make_pair(5,9));
89 
90     for(int i=0; i<5; i++) {
91         int Update(p[i]);
92     }  
93 }

　　在主函数中调用Update函数时，出现如下错误：

　　有待后续解决！！！