C + + parsing JSON

Boost parsing JSON

To include a header file:

#include <boost/property_tree/ptree.hpp>
#include <boost/property_tree/json_parser.hpp>

/*g++-o json_test json_test.cpp*/#include<boost/property_tree/ptree.hpp>#include<boost/property_tree/json_parser.hpp>#include<string>#include<sstream>#include<fstream>using namespacestd;using namespaceboost::p roperty_tree;voidCreate_json () {Ptree Pt_1,pt_11,pt_12; Pt_11.put ("ID","3445"); Pt_11.put (" Age", in); Pt_11.put ("name","Chen"); 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;
/* Generate file Ofstream.h

Ofstream Myofstream ("Json.txt");
Myofstream<<os.str ();
Myofstream.close ();

*/     } int Main () {         Create_json ();}

Output:

{    "Data": [        {            "ID":"3445",            " Age":" in",            "name":"Chen"        },        {            "ID":"3445",            " Age":" in",            "name":"Chen"        }    ]}

Parse the above:

voidParse_json () {Ifstreaminch("Json.txt"); Vector<string>Vecid; Vector<int>Vecage; Vector<string>Vecname;   Ptree PT,P1,P2; Read_json <ptree> (  in , PT); P1=pt.get_child ("Data");  for(Ptree::iterator it=p1.begin (); It!=p1.end (); it++) {P2=it->second;//First is empty        stringIdstr=p2.Get<string> ("ID");                Vecid.push_back (IDSTR); intAge=p2.Get<int> (" Age");                Vecage.push_back (age); stringNamestr=p2.Get<string> ("name");            Vecname.push_back (NAMESTR); } copy (Vecid.begin (), Vecid.end (), Ostream_iterator<string> (cout,"\ t")); Copy (Vecage.begin (), Vecage.end (), Ostream_iterator<int> (cout,"\ t")); Copy (Vecname.begin (), Vecname.end (), Ostream_iterator<string> (cout,"\ t")); }

An article:

Next, assign the above JSON string to a variable

String Strjson ={"People": [{"FirstName": "Brett", "LastName": "McLaughlin", "email": "AAAA"},

{"FirstName": "Jason", "LastName": "Hunter", "email": "BBBB"},

{"FirstName": "Elliotte", "LastName": "Harold", "email": "CCCC"}]}

Note: in C + + you need to "precede" to "add" to the intention.

Next, add the following variables to the program:

String stra,strc;
Vector<string> Vecstr;
Ptree PT,P1,P2;
StringStream stream;

The following program is parsing JSON

Stream << Strjson;
Read_json<ptree> (Stream, PT);
P1 = Pt.get_child ("people");
for (Ptree::iterator it = P1.begin (); It! = P1.end (); ++it)
{
P2 = it->second; First is empty
Stra = p2.get<string> ("FirstName");
Vecstr.push_back (Stra);
}

In this way, there are three values in the VECSTR, Brett,jason,elliotte,json parsing is completed.

For the following JSON format,

{"Programmers": [{"FirstName": "Brett", "LastName": "McLaughlin", "email": "AAAA"}, {"FirstName": "Jason", "LastName ":" Hunter "," email ":" BBBB "}, {" FirstName ":" Elliotte "," LastName ":" Harold "," email ":" CCCC "}]," authors ": [{" FirstName ":" Isaac "," LastName ":" Asimov "," Genre ":" Science Fiction "}, {" FirstName ":" Tad "," LastName ":" Williams "," 　　Genre ":" Fantasy "}, {" FirstName ":" Frank "," LastName ":" Peretti "," Genre ":" Christian Fiction "}]," Musicians ": [ {"FirstName": "Eric", "LastName": "Clapton", "instrument": "Guitar"}, {"FirstName": "Sergei", "LastName": "Rachman Inoff "," Instrument ":" Piano "}]}

It is necessary to change the above two sentences slightly.

P1 = Pt.get_child ("Programmers");

Stra = p2.get<string> ("FirstName");

Compare it and find out what's different? is to modify the parameters a little bit. What if you want to get the FirstName inside musicians? As long as the P1 = Pt.get_child ("Programmers"), the parameters are changed to musicians;

If JSON is nested inside JSON, you need to add a Ptree variable PT3,PT4. Make

P3 = P2.get_child ("nested value");

for (Ptree::iterator ita = P3.begin (); ITA! = P3.end (); ++ita)
{
P4 = ita->second;
STRC = p4.get<string> ("Markeritemlink");
}

Related source code please visit address

http://download.csdn.net/detail/yqmfly/3729591

There are questions to leave a message.

http://blog.csdn.net/yqmfly/article/details/6914590

More:

http://blog.csdn.net/dotphoenix/article/details/27081377

C + + parsing JSON