#include #include #include using json_document = nlohmann::json_document; int main() { std::cout << std::boolalpha; // long enough that copying it needs a real (heap) allocation, so the // comparison below does not depend on the standard library's small // string optimization threshold const std::string text = std::string(200, ' ') + "[1, 2, 3, 4, 5]"; // memory_usage() is not portable across platforms/allocators/compilers, so // compare it relatively instead of printing the raw byte count json_document borrowed = json_document::parse(text); json_document owned = json_document::parse_copy(text); // the owned document additionally stores its own copy of the source text std::cout << (owned.memory_usage() > borrowed.memory_usage()) << '\n'; // a document with more values needs a larger index json_document small = json_document::parse(std::string("[1]")); json_document large = json_document::parse(std::string("[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]")); std::cout << (large.memory_usage() > small.memory_usage()) << '\n'; }