Nikel Arteta Nikel Arteta - 2 months ago 46
C++ Question

get array data from json file using rapidjson

I'm new in rapidjson. I have

test.json
which contains
{"points": [1,2,3,4]}


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());


and its result is

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


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}]}


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; }


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

Any helps would be appreciated.

Thanks.

Answer Source

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());
}

and the output is

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

Hope it helps. :D