Summary - Serialization
- C++ course
- Advanced
- Lesson 54/83
- 5 min
Combine binary, JSON and versioning to write a config file.
Summary: a configuration file
In this summary you will combine binary, JSON and versioning for a configuration file. You will serialize the name and value fields of a Config struct as JSON and add a version field.
With the JSON library you create a nlohmann::json object. You set the j["name"], j["value"] and j["version"] fields. j.dump() produces the configuration file as a string. This is both human readable and version aware; it is a common approach in real projects.
Practice Write a versioned JSON configuration
Add #include <nlohmann/json.hpp>. Define nlohmann::json j;. Set j["name"] = "Alex";, j["value"] = 42; and j["version"] = 1;. Print with std::cout << j.dump();.
Starter code
#include <iostream>
#include <string>
// Add the nlohmann/json header and versioned JSON
int main() {
// Create JSON, add a version and print it
return 0;
}Sample solution
#include <iostream>
#include <nlohmann/json.hpp>
int main() {
nlohmann::json j;
j["name"] = "Alex";
j["value"] = 42;
j["version"] = 1;
std::cout << j.dump();
return 0;
}Expected output
{"name":"Alex","value":42,"version":1}
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 What do JSON + versioning provide?
- Binary only data
- Faster compilation
- Readable and versioned configuration Correct answer
- Less memory
Explanation: JSON is readable, versioning adds version control.
2 Complete the dump call
std::cout << j.____();std::cout << j.dump();Explanation: j.dump() returns the JSON object as a string.
3 Match the method to its role
| Term | Meaning |
|---|---|
binary write |
Writes bytes |
text << >> |
Writes/reads text |
nlohmann::json |
JSON object |
version field |
Version check |