Linux系统下如何使用C++解析json文件详解

{
   "age" : 21,
   "friends" : {
      "friend_age" : 21,
      "friend_name" : "ZhaoWuxian",
      "friend_sex" : "man"
   },
   "hobby" : [ "sing", "run", "Tai Chi" ],
   "name" : "shuiyixin",
   "sex" : "man"
}

#include <iostream>
#include <json/json.h>
#include <fstream>
 
using namespace std;
 
void readFileJson()
{
        Json::Reader reader;
        Json::Value root;
 
        //从文件中读取，保证当前文件有demo.json文件  
        ifstream in("demo.json", ios::binary);
 
        if (!in.is_open())
        {
                cout << "Error opening file\n";
                return;
        }
 
        if (reader.parse(in, root))
        {
                //读取根节点信息  
                string name = root["name"].asString();
                int age = root["age"].asInt();
                string sex = root["sex"].asString();
 
                cout << "My name is " << name << endl;
                cout << "I'm " << age << " years old" << endl;
                cout << "I'm a " << sex << endl;
				
				//读取子节点信息  
                string friend_name = root["friends"]["friend_name"].asString();
                int friend_age = root["friends"]["friend_age"].asInt();
                string friend_sex = root["friends"]["friend_sex"].asString();
 
                cout << "My friend's name is " << friend_name << endl;
                cout << "My friend's sex is "<<friend_sex << endl;
                cout << "My friend is " << friend_age << " years old" << endl;
 
                //读取数组信息  
                cout << "Here's my hobby:" << endl;
                for (unsigned int i = 0; i < root["hobby"].size(); i++)
                {
                        string ach = root["hobby"][i].asString();
                        cout << ach << '\t';
                }
                cout << endl;
 
                cout << "Reading Complete!" << endl;
        }
        else
        {
                cout << "parse error\n" << endl;
        }
 
        in.close();
}
 
int main(void)
{
        readFileJson();
        return 0;
}

#include <iostream>
#include <json/json.h>
#include <fstream>
 
using namespace std;
 
 
void writeFileJson()
{
	//根节点  
	Json::Value root;
 
	//根节点属性  
	root["name"] = Json::Value("shuiyixin");
	root["age"] = Json::Value(21);
	root["sex"] = Json::Value("man");
 
	//子节点  
	Json::Value friends;
 
	//子节点属性  
	friends["friend_name"] = Json::Value("ZhaoWuxian");
	friends["friend_age"] = Json::Value(21);
	friends["friend_sex"] = Json::Value("man");
 
	//子节点挂到根节点上  
	root["friends"] = Json::Value(friends);
 
	//数组形式  
	root["hobby"].append("sing");
	root["hobby"].append("run");
	root["hobby"].append("Tai Chi");
 
	//直接输出  
	//cout << "FastWriter:" << endl;
	//Json::FastWriter fw;
	//cout << fw.write(root) << endl << endl;
 
	//缩进输出  
	cout << "StyledWriter:" << endl;
	Json::StyledWriter sw;
	cout << sw.write(root) << endl << endl;
 
	//输出到文件  
	ofstream os;
	os.open("demo.json", std::ios::out | std::ios::app);
	if (!os.is_open())
		cout << "error：can not find or create the file which named \" demo.json\"." << endl;
	os << sw.write(root);
	os.close();
 
}
 
 
int main(void)
{
        writeFileJson();
        return 0;
}

#include <iostream>
#include <json/json.h>
#include <fstream>
 
using namespace std;
 
 
void readStrJson()
{
	//字符串  
	const char* str =
	"{\"name\":\"shuiyixin\",\"age\":\"21\",\"sex\":\"man\"}";
//	"{
//		"name" : "shuiyixin",
//		"age" : "21",
//		"sex" : "man"
//	}";
 
 
	Json::Reader reader;
	Json::Value root;
 
	//从字符串中读取数据  
	if (reader.parse(str, root))
	{
		string name = root["name"].asString();
		int age = root["nomen"].asInt();
		string sex = root["sex"].asString();
		cout << name + "," << age << "," << sex <<  endl;
	}
 
}
 
int main(void)
{
        readStrJson();
        return 0;
}

#include <iostream>
#include <json/json.h>
#include <fstream>
 
using namespace std;
 
void readStrProJson()
{
	string strValue = "{\"name\":\"shuiyixin\",\"major\":[{\"AI\":\"MachineLearning\"},{\"AI\":\"DeepLearning\"},{\"AI\":\"ComputerVision\"}]}";
	
	/*
	{
		"name":"shuiyixin",
		"major":[
		{
			"AI":"MachineLearning"
		},
		{
			"AI":"DeepLearning"
		},
		{
			"AI":"ComputerVision"
		}]
	}
	*/
	
	
	Json::Reader reader;
	Json::Value value;
	if (reader.parse(strValue, value))
	{
		string out = value["name"].asString();
		cout << out << endl;
		const Json::Value arrayObj = value["major"];
		for (unsigned int i = 0; i < arrayObj.size(); i++)
		{
			out = arrayObj[i]["AI"].asString();
			cout << out<<endl;
		}
	}
}
 
int main(void)
{
        readStrProJson();
        return 0;
}