Explain the use of C++ JSON static link library JsonCpp

JsonCpp deployment method:
In http: / / sourceforge net/projects jsoncpp/download the latest version of jsoncpp library source code.
Then unzip jsoncpp-src-version number -tar.gz, open jsoncpp.sln in makefiles and compile it. Then there will be a.lib static link library in vs71\debug\lib_json in build folder.

JsonCpp mainly includes three types of class:Value Reader Writer.

All object and class names in jsoncpp are in namespace json, including json.h

Json::Value    : can represent all supported types, such as int, double,string, object, etc Json::Reader: parses a file stream or string creation into Json::Value, mainly using the parse function. Json::Writer  :  , as opposed to JsonReader, converts Json::Value into a string stream, etc.

Note :Jsoncpp's Json::Writer class is a pure virtual class and cannot be used directly. Here we use the subclasses of Json::Writer: Json::FastWriter, Json::StyledWriter, Json::StyledStreamWriter.

Deserialize Json (parse Json)

{ 
  "name": "xiaoming " , 
  "like": [ 
    { 
      "book": "json" 
    }, 
    { 
      "food": "apple" 
    }, 
    { 
      "music": "sdds" 
    } 
  ] 
} 
 
void ReadJson()  
{ 
  std::string strValue = "{\"name\":\"xiaoming\",\"like\":[{\"book\":\"json\"},{\"food\":\"apple\"},{\"music\":\"sdds\"}]}"; 
 
  Json::Reader reader; 
  Json::Value value; 
 
  if (reader.parse(strValue, value)) 
  {   
    std::string out = value["name"].asString(); 
    std::cout << out << std::endl; 
    const Json::Value arrayObj = value["like"]; 
    for (unsigned int i = 0; i < arrayObj.size(); i++) 
    {   
      if (!arrayObj[i].isMember("book"))  
        continue; 
      out = arrayObj[i]["book"].asString(); 
      std::cout << out; 
      if (i != (arrayObj.size() - 1))  
        std::cout << std::endl; 
    }   
  }   
} 

Serialize Json(generate Json):

void WriteJson()  
{ 
  Json::Value root; 
  Json::Value arrayObj; 
  Json::Value item; 
 
  item["food"] = "apple"; 
  item["music"] = "JZhou"; 
  item["book"] = "json"; 
  arrayObj.append(item); 
 
  root["name"] = "xiaoming"; 
  root["like"] = arrayObj; 
 
  root.toStyledString(); 
  std::string out = root.toStyledString(); 
  std::cout << out << std::endl; 
} 

socket transmission via JSON
1. Client:

#include "json//json.h" 
#include <WinSock2.h> 
 
#pragma comment(lib, "WS2_32.lib") 
#pragma comment(lib, "json_vc71_libmtd.lib") 
 
int main() 
{ 
  Json::Value val; 
  Json::StyledWriter style_write; 
 
  val["name"] = "xiaoli" ; 
 
  WSADATA wsaData; 
  SOCKET SendSocket; 
  sockaddr_in RecvAddr; 
  int Port = 27015; 
   
  // Initialize the Socket 
  WSAStartup(MAKEWORD(2, 2), &wsaData); 
  // create Socket object  
  SendSocket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP); 
  // Set the server address  
  RecvAddr.sin_family = AF_INET; 
  RecvAddr.sin_port = htons(Port); 
  RecvAddr.sin_addr.s_addr = inet_addr("127.0.0.1"); 
 
  std::string SendBuf = style_write.write(val); 
 
  // Send data to the server  
  sendto(SendSocket, SendBuf.c_str(), SendBuf.size(), 0, (SOCKADDR*)&RecvAddr, sizeof(RecvAddr)); 
 
  closesocket(SendSocket); 
  WSACleanup(); 
 
  getchar(); 
  return 0; 
} 

2. Server side:

#include <iostream> 
#include <WinSock2.h> 
#include "json/json.h" 
 
#pragma comment(lib, "WS2_32.lib") 
#pragma comment(lib, "json_vc71_libmtd.lib") 
int main() 
{ 
  // Initialize the socket 
  WSADATA wsaData; 
  WSAStartup(MAKEWORD(2,2), &wsaData); 
  // create socket 
  SOCKET RecvSocket; 
  RecvSocket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP); 
  // Set the server address  
  sockaddr_in RecvAddr; 
  int Port = 27015; 
  RecvAddr.sin_family = AF_INET; 
  RecvAddr.sin_port = htons(Port); 
  RecvAddr.sin_addr.s_addr = htonl(INADDR_ANY); 
  // The binding socket 
  bind(RecvSocket, (SOCKADDR*)&RecvAddr, sizeof(RecvAddr)); 
 
  char RecvBuf[1024]; 
  int BufLen = 1024; 
  sockaddr_in SenderAddr; 
  int SendAddrSize = sizeof(SenderAddr); 
 
  recvfrom(RecvSocket, RecvBuf, BufLen, 0, (SOCKADDR*)&SenderAddr, &SendAddrSize); 
 
  std::string strName; 
  Json::Value val; 
  Json::Reader reader; 
  if (reader.parse(RecvBuf, val)) 
  { 
    strName = val["name"].asString(); 
  } 
 
  std::cout << strName << std::endl; 
 
  closesocket(RecvSocket); 
  WSACleanup(); 
 
  getchar(); 
  return 0; 
}