Notice:

1. Functions defined in C + + should have destructors
2. The custom header file in C + + needs

#ifndef CODE_CPP_GLOBAL_H
#define CODE_CPP_GLOBAL_H

#endif //CODE_CPP_GLOBAL_H

3. When inserting key value pairs into the map in C + +, you must first check whether the key exists, because:
-a. if you insert the same key, no error will be reported at compile time and run time
-b. if the key value of the inserted data already exists, the insertion operation will be ignored

About C++

1. Constructor and destructor of class~

Rookie tutorial: constructor and destructor of C + + class

2. heavy haul

(1) overloaded operators and overloaded functions
(2) I / O operator overload

3. Quotation summary

https://www.cnblogs.com/jycboy/p/5184638.html

4.double rounded to int

double qty;
int i_qty = (int) (qty + 0.5);

5. sort function call

(1) https://www.cnblogs.com/jjzzx/p/5122381.html
(2) use the iterator (reverse iterator) to sort in order (reverse order). The default is from small to large:

Order:

#include<iostream>
#include<algorithm>
#include<cstring>
using namespace std;
int main()
{
    string str("hello world");
    sort(str.begin(),str.end());
    cout<<str;
    return 0;
 } 

//Result: the space dehllorw

Reverse order:

#include<iostream>
#include<algorithm>
#include<cstring>
using namespace std;
int main()
{
   string str("hello world");
   sort(str.rbegin(),str.rend());
   cout<<str;
   return 0;
} 

//Result: wroollhde space

6. Keyword auto

auto can automatically select the matching type for this variable according to the type of initial value of the variable when declaring the variable, which is used to replace the lengthy and complex variable declaration with a specific range of variables.

7.map traversal

For a map, the following two lines of loops are wrong, and the map cannot be traversed as follows with i:

   for(int i=0; i<map.size();  i++) 
   TaskInfo* pInfo = map[i];

A proper traversal:

map<char,string> mp;
map<char,string>::iterator it;
int main(int argc, char const *argv[])
{
　　mp['0']="0000";mp['1']="0001";mp['2']="0010";
　　mp['3']="0011";mp['4']="0100";mp['5']="0101";
　　mp['6']="0110";mp['7']="0111";mp['8']="1000";
　　mp['9']="1001";mp['A']="1010";mp['B']="1011";
　　mp['C']="1100";mp['D']="1101";mp['E']="1110";
　　mp['F']="1111";
   for(it = mp.begin(); it != mp.end(); it++)
       cout<<it->first<<":"<<it->second<<endl;
　　　　 //It - > the value of the first subscript, it - > the value of the second subscript
   return 0;
}

File input and output

(1)
The content of Benchmark.txt is as follows:

620000044158676000	1	A10	33.200520833333336
620000044135169000	9	A11	49.76450704225352
620000044128782000	1	A02	35.15409035409036
620000044128968000	1	A02	59.412454212454215
620000044129080000	1	A02	56.10329670329671
620000044130416000	1	A14	71.11111111111111
620000044126894000	2	A09	42.328711528429835
620000044126899000	2	A03	66.66666666666667
620000044136505000	1	A08	42.30769230769231
620000044136571000	1	A08	46.36923076923077
620000044137207000	1	A12	16.768559272300468
620000044131144000	2	A03	60.827481481481485
620000044132226000	2	A13	78.73167701863353
620000044139178000	4	A08	53.53641025641026
620000044162027000	1	A02	68.33191697191697
620000044106464000	3	A09	71.75880020865937

C++ Code:

#include <iostream>
#include <fstream>
#include <string>
#include <cassert>
#include <map>

using namespace std;

class problem{
public:
    problem(){};
    ~problem(){};
public:
    std::string oid;
    int qty;
    std::map<int, int> num;
    std::string benchmark_sol_carton;
    double benchmark_sol_utl;
};

int main() {
    std::map<std::string, problem> map_order;
    std::map<std::string, problem>::iterator it;
    string filename = "Benchmark.txt";
    ifstream fin(filename.c_str());
    string line;
    // output lines in Benchmark.txt
    while(getline(fin, line)){
        cout<<line<<endl;
    }
    fin.close();

    // set value for map_order
    fin.open(filename.c_str());
    if(fin.fail()){
        std::cerr << "File open failed: " + filename << std::endl;
    }
    std::string or_id;
    while(fin >> or_id){
        problem & o = map_order[or_id]; // if map_order[or_id] doesn't exsit,
        fin >> o.qty;
        fin >> o.benchmark_sol_carton >> o.benchmark_sol_utl;
    }
    fin.close();

    // check the value of map_order
    for (it = map_order.begin(); it != map_order.end(); ++it)
        cout << it->first << " = " << it->second.qty << endl;

    return 0;
}

Operation result:

620000044158676000	1	A10	33.200520833333336
620000044135169000	9	A11	49.76450704225352
620000044128782000	1	A02	35.15409035409036
620000044128968000	1	A02	59.412454212454215
620000044129080000	1	A02	56.10329670329671
620000044130416000	1	A14	71.11111111111111
620000044126894000	2	A09	42.328711528429835
620000044126899000	2	A03	66.66666666666667
620000044136505000	1	A08	42.30769230769231
620000044136571000	1	A08	46.36923076923077
620000044137207000	1	A12	16.768559272300468
620000044131144000	2	A03	60.827481481481485
620000044132226000	2	A13	78.73167701863353
620000044139178000	4	A08	53.53641025641026
620000044162027000	1	A02	68.33191697191697
620000044106464000	3	A09	71.75880020865937
620000044106464000 = 3
620000044126894000 = 2
620000044126899000 = 2
620000044128782000 = 1
620000044128968000 = 1
620000044129080000 = 1
620000044130416000 = 1
620000044131144000 = 2
620000044132226000 = 2
620000044135169000 = 9
620000044136505000 = 1
620000044136571000 = 1
620000044137207000 = 1
620000044139178000 = 4
620000044158676000 = 1
620000044162027000 = 1

Process finished with exit code 0