Using C + + to try out JSON third party library jsoncpp__c++

JSON is a lightweight data-definition format, and it's a good choice to use for data exchange compared to XML, which is easy to learn, and not much worse than XML.

The full name of JSON is: JavaScript Object notation, as the name suggests, JSON is used to mark JavaScript objects, and details refer to http://www.json.org/.

This article selects the third party library Jsoncpp to parse Json,jsoncpp is the more famous C + + analytic library, in the JSON official website is also the most notable.

Jsoncpp Introduction

Jsoncpp consists of three types of Class:value Reader Writer.

All objects in Jsoncpp, class names in namespace json, contain json.h.

Note: Json::value can only handle ANSI-type strings, and if the C + + program uses Unicode encoding, it is best to add a adapt class to fit.

Download and compile

The operating environment of this article is: Redhat 5.5 + g++version 4.6.1 + GNU make 3.81 + jsoncpp-0.5.0

Download address is: http://sourceforge.net/projects/jsoncpp/

After decompression get jsoncpp-src-0.5.0 folder, we only need Jsoncpp header file and CPP file, where Jsonscpp header file is located in Jsoncpp-src-0.5.0includejson, The Jsoncpp CPP file is located in Jsoncpp-src-0.5.0srclib_json.

Here I list our working directory:

jsoncpp///working directory

| |--INCLUDE//header file root directory

| |--JSON//json header file, corresponding to Jsoncpp-src-0.5.0includejson

|--src//cpp source file root directory

|--JSON//jsoncpp source file, corresponding to Jsoncpp-src-0.5.0srclib_json

|--main.cpp//Our main function, call Jsoncpp sample code

|--Makefile//makefile, do not let us say more, do not understand please see my blog makefile best Practice

Deserialize a JSON object

Suppose you have a JSON object as follows:

{"Name": "Json″," array: [{"CPP": "Jsoncpp"}, {"Java": "Jsoninjava"}, {"PHP": "Support"}] }

We want to implement this JSON's reverse sequence code as follows:

Voidreadjson () {usingnamespacestd; Std::stringstrvalue = "{\ name\": \ "json\", \ "array\": [{\ "cpp\": \ "Jsoncpp\"},{\ "java\": \ "Jsoninjava\"},{\ "php\": \ "   Support\ "}]}";   Json::reader Reader;   Json::value Value;   if (Reader.parse (strvalue, value)) {std::stringout= value["name"].asstring ();   Std::cout <<out<<std::endl;   　Constjson::value arrayobj = value["Array"];   for (unsigned inti = 0;i <arrayobj.size (); i++) {if (!arrayobj[i].ismember ("CPP")) continue;   out= arrayobj[i]["CPP"].asstring ();   Std::cout <<out;   　if (I!= (Arrayobj.size ()-1)) Std::cout <<std::endl; }   }   }

Serialization of JSON objects

Voidwritejson ()  {  USINGNAMESPACESTD   json::value root;   json::value arrayobj;   json::value item;   item["cpp"] =  "Jsoncpp";   item["java"] =  "Jsoninjava";   item["PHP"] =  "support";   Arrayobj.append (item);   root["name"] =  "JSON";   root["Array"] = arrayobj;   Root.tostyledstring ();   Std::stringout= root.tostyledstring ();   std::cout <<out<<std::endl;  }