c++ rapidjson 解析本地 json 文件

概述

使用 rapidjson 来解析本地的 json 文件。

本地 json 文件

{
    "num": 3,
    "subject": [
        "Math",
        "English",
        "Computer Science"
    ],
    "info": [
        {
            "value": "线性代数",
            "score": 70,
            "aveScore": 75.8
        },
        {
            "value": "四六级",
            "score": 500,
            "aveScore": 410.8
        },
        {
            "value": "数据结构",
            "score": 88,
            "aveScore": 65.4
        }
    ]
}

代码

#include <iostream>
#include <string>
#include <fstream>
#include <windows.h>
#include "rapidjson/prettywriter.h"
#include "rapidjson/document.h"
#include "rapidjson/istreamwrapper.h"

using namespace std;
using namespace rapidjson;

//-----------------------------------------------------------------------------
wstring UTF8ToUnicode(const string &s)
{
	wstring result;

	// 获得缓冲区的宽字符个数
	int length = MultiByteToWideChar(CP_UTF8, 0, s.c_str(), -1, NULL, 0);

	wchar_t * buffer = new wchar_t[length];
	::MultiByteToWideChar(CP_UTF8, 0, s.c_str(), -1, buffer, length);
	result = buffer;

	delete[] buffer;
	return result;
}

//-----------------------------------------------------------------------------
int main()
{
	int n;
	int score[3];
	double aveScore[3];
	string strSubject[3];
	wstring wsValue[3];

	ifstream t("document.json"); // 输入流
	IStreamWrapper isw(t);
	Document d;
	d.ParseStream(isw);

	// 获取最简单的单个键的值
	assert(d.HasMember("num"));
	assert(d["num"].IsInt());
	n = d["num"].GetInt();

	// 获取数组的值,使用引用来连续访问
	assert(d.HasMember("subject"));
	const Value& subjectArray = d["subject"];
	if (subjectArray.IsArray())
	{
		for (int i = 0; i < subjectArray.Size(); i++)
		{
			strSubject[i] = subjectArray[i].GetString();
		}
	}

	// 获取对象中的数组，也就是对象是一个数组
	assert(d.HasMember("info"));
	const Value& infoArray = d["info"];
	if (infoArray.IsArray()) {
		for (int i = 0; i < infoArray.Size(); i++) {
			const Value& tempInfo = infoArray[i];

			string strValue = tempInfo["value"].GetString();
			wsValue[i] = UTF8ToUnicode(strValue);

			score[i] = tempInfo["score"].GetInt();
			aveScore[i] = tempInfo["aveScore"].GetDouble();
		}
	}
}