json的解析

#include <stdio.h>
#include <string>
using namespace std;

/* jsoncpp support */
#include "jsoncpp/json.h" // JSON构造与解析


// 从文件中读取字符串
string readfile (const char* filename)
{
    FILE* fp = fopen(filename, "rb");
    if(!fp)  //检查文件是否错误
    {
        printf("failed to open file! file: %s" , filename);
        return "";
    }
    char* buf = new char[1024*16];  //新建缓冲区
    int n = fread(buf, 1, 1024*16, fp);
    fclose(fp);

    string result;
    if(n >= 0)
        result.append(buf, 0, n);
    delete [] buf;

    return result;
}

int parseJSON (const char* jsonstr)
{
    Json::Reader reader;
    Json::Value resp;
    if (!reader.parse(jsonstr, resp, false))
        throw string("bad json format!\n");

    int errorCode = resp["errorCode"].asInt();
    string reason = resp["reason"].asString();
    if(errorCode != 0)
        throw string(reason);

    Json::Value& result = resp["result"];
    if(result.isObject())
    {
        int userId = result["userId"].asInt();
        string name = result["name"].asString();
        printf("userId:%d,  name: %s\n", userId, name.c_str());
    }
    printf("show numbers:\n");
    Json::Value& numbers = resp["numbers"];
    for(int i=0; i<numbers.size() ; i++)
    {
        Json::Value& jvalue = numbers[i];
        int n = jvalue.asInt();
        printf("%d ,", n);
    }

    return 0;
}


int main()
{
    string jsonstr = readfile("example.json");
//    printf("%s", jsonstr.c_str());

    /* 使用异常机制会方便一些 */
     try{
         parseJSON(jsonstr.c_str());    
    }catch(string e)
    {
        printf("解析错误: %s \n", e.c_str());
    }
    return 0;
}