rapidjson object as function argument cause compiler error
rapidjson, reference
Solution
You cannot pass a `Document` as value, you must pass it by reference or pointer. This is because `Document` is not copy-able.
I suggest this function declaration in your situation:
std::string json_to_string(const rapidjson::Document& jmsg)
Problem
I try to pass rapidjson::Document object as function argument: ``` std::string json_to_string(rapidjson::Document jmsg) { // Convert JSON document to string rapidjson::StringBuffer buffer; rapidjson::Writer< rapidjson::StringBuffer > writer(buffer); jmsg.Accept(writer); std::string str = buffer.GetString(); return str; } ``` If I do the function just as above, I got this error when I compile the code: In function `rapidjson::GenericDocument, rapidjson::MemoryPoolAllocator >::GenericDocument(rapidjson::GenericDocument, rapidjson::MemoryPoolAllocator > const&)': ../../rapidjson/document.h:691: undefined reference to `rapidjson::GenericValue, rapidjson::MemoryPoolAllocator >::GenericValue(rapidjson::GenericValue, rapidjson::MemoryPoolAllocator > const&)' collect2: error: ld returned 1 exit status The error disappears if I change the argument type from "rapidjson::Document jmsg" to "rapidjson::Document &jmsg". Use the reference is ok, however, I still want to know what's wrong with the code if I don't define it as a reference type.