json+c++

boost生成和解析json实例及定向到文件

添加boost：

1.点击还原NuGet包 

1.

2.点击第一个安装

3. cpp代码中加载头文件即可

生成json

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1. // test.cpp  
2. #include <iostream>  
3. #include <string>  
4. #include <boost/property_tree/ptree.hpp>  
5. #include <boost/property_tree/json_parser.hpp>  
6. #include <boost/foreach.hpp>  
7. using namespace std;  
8. using namespace boost::property_tree;  
9.    
10. int main(){  
11.     ptree pt_1,pt_11,pt_12;  
12.      
13.     pt_11.put("id","3445");  
14.     pt_11.put<int>("age",29);  
15.     pt_11.put("name","chen");     
16.      
17.     pt_12.push_back(make_pair("",pt_11));  
18.     pt_12.push_back(make_pair("",pt_11));  
19.     //replace or create child node "data"  
20.     pt_1.put_child("data",pt_12);     
21.     ostringstream os;  
22.     write_json(os,pt_1);  
23.     cout<<os.str()<<endl;  
24.     system("pause");  
25.     return 0;  
26. }  
27. // =========== 产生如下JSON串： ===============  
28.     /*  
29.     {  
30.     "data":  
31.         [  
32.             {  
33.                 "id": "3445",  
34.                 "age": "29",  
35.                 "name": "chen"  
36.             },  
37.             {  
38.                 "id": "3445",  
39.                 "age": "29",  
40.                 "name": "chen"  
41.             }  
42.         ]  
43.     }  
44.     */  

生成json

格式为：

#include <iostream>  #include <string>  #include <boost/property_tree/ptree.hpp>  #include <boost/property_tree/json_parser.hpp>  #include <boost/foreach.hpp> #include<opencv2/opencv.hpp> #include<vector>using namespace std;using namespace cv;using namespace boost::property_tree;int main() {//ptree pt_1, pt_11, pt_12;//pt_11.put("id", "3445");//pt_11.put<int>("age", 29);//pt_11.put("name", "chen");//pt_12.push_back(make_pair("", pt_11));//pt_12.push_back(make_pair("", pt_11));//pt_12.push_back(make_pair("", pt_11));////replace or create child node "data"  //pt_1.put_child("data", pt_12);//ostringstream os;//write_json(os, pt_1);//cout << os.str() << endl;//system("pause");//return 0;vector<Point> points;Point point1 = { 1,2 };Point point2 = { 3,4 };points.push_back(point1);points.push_back(point2);ptree pt_1,  pt_12,pt_121,pt_1211, pt_122;int a = 20;pt_1.put<int>("code", a);//pt_1.put("data", pt_12);pt_121.put("url", "h");pt_121.put<int>("people_num", 2);pt_121.put<int>("is_high_density", 0);//pt_122.put<int>("is_high_density", 0);//pt_121.put<int>("x", points[0].x);for (int i = 0; i < points.size(); i++) {pt_1211.put<int>("x", points[i].x);pt_1211.put<int>("y", points[i].y);//pt_121.put("x","y", points[i]);//pt_121.put<int>("y", points[i].y);//cout << points[i].x;//cout << points[i].y;pt_122.push_back(make_pair("", pt_1211));}//pt_122.push_back(make_pair("", pt_1211));//pt_122.push_back(make_pair("", pt_1211));pt_121.put_child("people_point", pt_122);pt_12.push_back(make_pair("", pt_121));//pt_122.push_back(make_pair("", pt_1211));pt_1.put_child("data", pt_12);//pt_121.put_child("people_point", pt_122);ostringstream os;write_json(os, pt_1);cout << os.str() << endl;system("pause");return 0;}

运行截图：

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1. #include <boost/property_tree/ptree.hpp>  
2. #include <boost/property_tree/json_parser.hpp>  
3. #include <boost/foreach.hpp>  

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1. void downgadget::Downloader_c::makereport(const downloaderInfo_t info)  
2. {  
3.     using boost::property_tree::ptree;  
4.     ptree downloaderInfo ;  
5.   
6.   
7.     downloaderInfo.put("id",info.id);  
8.     downloaderInfo.put("code",info.code);  
9.     downloaderInfo.put("mesg",info.mesg);  
10.     downloaderInfo.put("path",info.path);  
11.     downloaderInfo.put("md5sum",info.md5sum);  
12.     downloaderInfo.put("size",info.size);  
13.     downloaderInfo.put("url",info.url);  
14.     downloaderInfo.put("time_download",info.time_download);  
15.     downloaderInfo.put("time_install",info.time_install);  
16.     downloaderInfo.put("cmd_install",info.cmd_install);  
17.   
18.     std::ostringstream os;  
19.     write_json(os,downloaderInfo);  
20.     std::cout<<os.str()<<std::endl;  
21.   
22.     std::ofstream tmpReport(m_reportPath);  
23.     if(!tmpReport){  
24.         std::cout<<"critical error open output report error!"<<std::endl;  
25.     }else{  
26.         tmpReport<<os.str();  
27.     }  
28.     tmpReport.close();  
29. }  

已知 json 直接遍历所有：

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1. #include <iostream>  
2. #include <string>  
3. #include <boost/property_tree/ptree.hpp>  
4. #include <boost/property_tree/json_parser.hpp>  
5. #include <boost/foreach.hpp>  
6. using namespace std;  
7. using namespace boost::property_tree;  

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1. string json_string="{\"-f\": \"/usr/reservedfff_dir\", \"-s\": \"/usr/reservedddd_dir\"}";  
2.   
3. string str_head;  
4. string str_node_val;  
5. ptree pt,p1,p2;  
6.   
7. stringstream stream;  
8. stream << json_string ;  
9. read_json<ptree>( stream, pt);  
10.   
11. for (ptree::iterator ita = pt.begin(); ita != pt.end(); ++ita)  
12. {  
13.     cout<<"first:"<<ita->first<<endl;  
14.     str_node_val = pt.get<string>(ita->first);  
15.     cout<<str_node_val<<endl;  
16. }  

加入exception:

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1. string json_string="{\"-f\": \"/usr/reservedfff_dir\" \"-s\": \"/usr/reservedddd_dir\"}";  
2.   
3. string str_head;  
4. string str_node_val;  
5. ptree pt,p1,p2;  
6.   
7. stringstream stream;  
8. stream << json_string ;  
9.   
10.   
11. try{  
12.     read_json<ptree>( stream, pt);  
13.     cout<<"parsing ok\n"<<endl;  
14.     for (ptree::iterator ita = pt.begin(); ita != pt.end(); ++ita)  
15.     {  
16.         cout<<"first:"<<ita->first<<endl;  
17.         str_node_val = pt.get<string>(ita->first);  
18.         cout<<str_node_val<<endl;  
19.     }  
20. }  
21. catch(std::runtime_error& e)  
22. {  
23.     std::cout<<e.what()<<endl;  
24. }