enum ValueType
{
      nullValue = 0, ///< ‘null‘ value
      intValue,      ///< signed integer value
      uintValue,     ///< unsigned integer value
      realValue,     ///< double value
      stringValue,   ///< UTF-8 string value
      booleanValue,  ///< bool value
      arrayValue,    ///< array value (ordered list)
      objectValue    ///< object value (collection of name/value pairs).
};

const char *asCString() const;
std::string asString() const;
Int asInt() const;
UInt asUInt() const;
Int64 asInt64() const;
UInt64 asUInt64() const;
LargestInt asLargestInt() const;
LargestUInt asLargestUInt() const;
float asFloat() const;
double asDouble() const;
bool asBool() const;

Json::Value root;
Json::Reader reader;

if(!reader.parse(str_data, root)){
    // error processing
}

// 这里一定要注意，如果不是array类型，这里的size函数返回的是key的个数
int array_size = root.size();
for(i=0;i<array_size;i++){
    Json::Value obj = root[i];
    // do something with obj
}

Json::Value arrayjson;

for (iterator) {
    Json::Value jsonobj;
    jsonobj["a"] = "b";
    arrayjson.append(jsonobj);
}

Json::FastWriter writer;
str = writer.write(root);