c++

python中multiprocessing.pool函数介绍_正在拉磨_新浪博客

    multiprocessing.pool

c++ - Create empty json array with jsoncpp - Stack Overflow

    Create empty json array with jsoncpp
    up vote 1 down vote favorite
    1
       

    I have following code:

    voidMyClass::myMethod(Json::Value& jsonValue_ref){for(int i =0; i <= m_stringList.size(); i++){if(m_boolMarkerList[i]){
                jsonValue_ref.append(stringList[i]);}}}voidMyClass::myOuterMethod(){Json::Value jsonRoot;Json::Value jsonValue;

        myMethod(jsonValue);

        jsonRoot["somevalue"]= jsonValue;Json::StyledWriter writer;
        std::string out_string = writer.write(jsonRoot);}

    If all boolMarkers are false the out_string is { "somevalue" : null } but I want it to be an empty array: { "somevalue" : [ ] }

    Does anybody know how to achieve this?

    Thank you very much!
    c++ json jsoncpp
    share|edit|flag
       
    asked Nov 8 '12 at 16:17
    Martin Meeser
    190110
        
          
          
    add comment
        
    start a bounty
    3 Answers
    active oldest votes
    up vote 5 down vote accepted
       

    You can do it also this way:

    jsonRootValue["emptyArray"]=Json::Value(Json::arrayValue);

    share|edit|flag
       
    answered Feb 28 '13 at 13:36
    user609441
    6613
        
          
          
    add comment
    up vote 1 down vote
       

    You can do this by defining the Value object as an "Array object" (by default it makes it as an "object" object which is why your member becomes "null" when no assignment made, instead of [] )

    So, switch this line:

    Json::Value jsonValue;
     myMethod(jsonValue);

    with this:

    Json::Value jsonValue(Json::arrayValue);
    myMethod(jsonValue);

    And voila! Note that you can change "arrayValue" to any type you want (object, string, array, int etc.) to make an object of that type. As I said before, the default one is "object".
    share|edit|flag
       
    answered Mar 4 '13 at 9:28
    Ahmet Ipkin
    528
        
         upvote
         flag
       
    Thank you Ahmet but this is exactly the same as user609441 already stated with a little more text. –  Martin Meeser Mar 5 '13 at 11:18
         upvote
         flag
       
    Wanted to explain the reasons as well ^_^ –  Ahmet Ipkin Mar 7 '13 at 7:29
          
    add comment
    up vote 0 down vote
       

    OK I got it. It is a little bit annoying but it is quite easy after all. To create an empty json array with jsoncpp:

    Json::Value jsonArray;
    jsonArray.append(Json::Value::null);
    jsonArray.clear();
    jsonRootValue["emptyArray"]= jsonArray;

    Output via writer will be:

    {"emptyArray"=[]}