Question

我的代码编译没有错误，但在运行时我收到以下错误 - ＆gt;

testGetprice2.o: rapidjson/include/rapidjson/document.h:1125: rapidjson::SizeType rapidjson::GenericValue<Encoding, Allocator>::Size() const [with Encoding = rapidjson::UTF8<>; Allocator = rapidjson::MemoryPoolAllocator<>; rapidjson::SizeType = unsigned int]: Assertion `IsArray()' failed.

失败的地方是我的for（）循环

std::cout << document[i]["lasttradeprice"].

我正在尝试查询subObject＆＃34; lasttradeprice＆＃34;但是没有错误地访问该对象。

如何正确查询子对象/摆脱此错误？

代码 - ＆gt;

#include "rapidjson/include/rapidjson/document.h"
#include <iostream>
#include <fstream>
#include <stdio.h>
#include <curl/curl.h>
#include <unistd.h>
#include <unordered_map>
#include <string>

using namespace rapidjson;

struct myData
{
    std::fstream *file;
    std::string *str;
};

size_t write_data(void *ptr, size_t size, size_t nmemb, myData *data)
{
    size_t numBytes = size * nmemb;

    if (data->file)
        data->file->write((char*)ptr, numBytes);

    if (data->str)
        *data->str += std::string((char*)ptr, numBytes);

    return numBytes;
}

//function to get coin data and perform analysis
int getData()
{
    int count = 0;

    //begin non terminating loop
    while(true)
    {
        count++;
        CURL *curl = curl_easy_init();
        if (curl)
        {
            curl_easy_setopt(curl, CURLOPT_URL, "http://pubapi.cryptsy.com/api.php?method=singlemarketdata&marketid=155");

            std::fstream file("/home/coinz/cryptsy/myfile.txt", std::ios_base::out | std::ios_base::ate);
            std::string json;

            myData data;
            data.file = &file;
            data.str = &json;

            curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, &write_data);
            curl_easy_setopt(curl, CURLOPT_WRITEDATA, &data);

            /* Perform the request, res will get the return code */
            CURLcode res = curl_easy_perform(curl);

            /* Check for errors */
            if (res != CURLE_OK)
            {
                std::cerr << "curl_easy_perform() failed: " << curl_easy_strerror(res) << std::endl;
            }
            else
            {
                file << std::endl;

                //begin deserialization
                Document document;
                document.Parse(json.c_str());
                for (SizeType i = 0; i < document.Size(); i++){
                    std::cout << document[i]["lasttradeprice"].GetString() << std::endl;
                }
                //assert(document.HasMember("return"));
                //assert(document["return"].IsString());
                //std::cout << "The Last Traded Price is = " << document["return"].GetString() << std::endl;
            }

            /* always cleanup */
            curl_easy_cleanup(curl);
        }

        //timer for URL request.  *ADUJST ME AS DESIRED*
        usleep(10000000);
    }

    return 0;
}

//Le Main
int main(void)
{
    getData();
}

gdb - ＆gt;

(gdb) run
Starting program: /home/coinz/cryptsy/testGetprice2.o
warning: Could not load shared library symbols for linux-vdso.so.1.
Do you need "set solib-search-path" or "set sysroot"?
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib64/libthread_db.so.1".
[New Thread 0x7ffff5cc9700 (LWP 24708)]
[Thread 0x7ffff5cc9700 (LWP 24708) exited]
testGetprice2.o: rapidjson/include/rapidjson/document.h:1125: rapidjson::SizeType rapidjson::GenericValue<Encoding, Allocator>::Size() const [with Encoding = rapidjson::UTF8<>; Allocator = rapidjson::MemoryPoolAllocator<>; rapidjson::SizeType = unsigned int]: Assertion `IsArray()' failed.

Program received signal SIGABRT, Aborted.
0x00007ffff6fec795 in raise () from /lib64/libc.so.6

Answer 1

根据原始JSON，结构如下：

{
  "success":1,
  "return":
  {
    "markets":
    {
      "DRK":
      {
        "marketid":"155",
        "label":"DRK\/BTC",
        "lasttradeprice":"0.00553336",
        "volume":"14615.30200941",
        "lasttradetime":"2014-10-25 14:35:09",
        "primaryname":"DarkCoin",
        "primarycode":"DRK",
        "secondaryname":"BitCoin",
        "secondarycode":"BTC",
        "recenttrades":

你想要访问

document[i]["lasttradeprice"]

但您应该访问

documents["return"]["markets"][i]["lasttradedprice"]

Answer 2

用

替换你的循环

std :: cout＆lt;＆lt; ＆＃34;最后交易价格=＆＃34; ＆LT;＆LT;文件[＆＃34;返回＆＃34;] [＆＃34;市场＆＃34;] [＆＃34; DRK＆＃34;] [＆＃34; lasttrad eprice＆＃34;]。GetString（）＆lt;＆lt;的std :: ENDL;

CSON查询JSON subObject错误

2 个答案: