使用rapidjson从json文件获取数组数据 [英] get array data from json file using rapidjson

问题描述

我是Rapidjson的新手.我有test.json其中包含{"points": [1,2,3,4]}

I'm new in rapidjson. I have test.json which contains {"points": [1,2,3,4]}

并且我使用以下代码获取数组"points"

and I use following code to get data of array "points"

std::string fullPath = CCFileUtils::sharedFileUtils()->fullPathForFilename("json/deluxe/treasurebag.json");

    unsigned long bufferSize = 0;

    const char* mFileData = (const char*)CCFileUtils::sharedFileUtils()->getFileData(fullPath.c_str(), "r", &bufferSize);

    std::string clearData(mFileData);
    size_t pos = clearData.rfind("}");
    clearData = clearData.substr(0, pos+1);
    document.Parse<0>(clearData.c_str());
    assert(document.HasMember("points"));

    const Value& a = document["points"]; // Using a reference for consecutive access is handy and faster.
    assert(a.IsArray());
    for (SizeType i = 0; i < a.Size(); i++) // rapidjson uses SizeType instead of size_t.
        CCLOG("a[%d] = %d\n", i, a[i].GetInt());

其结果是

Cocos2d: a[0] = 1
Cocos2d: a[1] = 2
Cocos2d: a[2] = 3
Cocos2d: a[3] = 4

符合预期.但是现在当我尝试从像这样的数组中获取数据(获取x和y)

as expected. But now when I try to get data (get x and y) from an array like this

{"points": [{"y": -14.25,"x": -2.25},{"y": -13.25,"x": -5.75},{"y": -12.5,"x": -7.25}]}

发生错误并在编译器中丢弃:

an error occured and threw away in compiler:

//! Get the number of elements in array.
    SizeType Size() const { RAPIDJSON_ASSERT(IsArray()); return data_.a.size; }

谁能解释我做错了什么或错过了什么?对不起，我的英语不好.

Can anyone explain what i did wrong or something's missed? Sorry for my bad English.

任何帮助将不胜感激.

谢谢.

推荐答案

最后我自己找到了，正确的语法是document["points"][0]["x"].GetString()

Finally found it myself, The correct syntax would be document["points"][0]["x"].GetString()

for (SizeType i = 0; i < document["points"].Size(); i++){
    CCLOG("{x=%f, y=%f}", document["points"][i]["x"].GetDouble(), document["points"][i]["y"].GetDouble());
}

输出为

Cocos2d: {x=-2.250000, y=-14.250000}
Cocos2d: {x=-5.750000, y=-13.250000}
Cocos2d: {x=-7.250000, y=-12.500000}

希望它会有所帮助. :D

Hope it helps. :D

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