foof.cpp

#include "rapidjson/document.h"
#include "rapidjson/writer.h"
#include "rapidjson/stringbuffer.h"
#include <iostream>

using namespace rapidjson;

int main() {
    const char* json = "{\"shit\":-1.1030161663305387}";
    Document d;
    d.Parse(json);

    StringBuffer buffer;
    Writer<StringBuffer> writer(buffer);
    d.Accept(writer);

    std::cout << json << std::endl;
    std::cout << buffer.GetString() << std::endl;
    return 0;
}

output, unexpectedly:

{"shit":-1.1030161663305387}
{"shit":-1.103016166330539}