Yet another JSON library. Parsing and printing is based on libjson.
#include <json.hpp>
Json data;
data["name"] = "John Doe";
data["age"] = 30;
data["role"] = "Developer";
data["address"]["number"] = 125;
data["address"]["street"] = "Maple Avenue";
data["address"]["city"] = "San Pedro";
data["address"]["state"] = "California";
data["address"]["zip_code"] = 90731;
data["skills"].push_back("C++");
data["skills"].push_back("Linux");
data["skills"].push_back("JSON");
std::cout << data.size() << std::endl; // Output: 5
std::cout << data["name"].to_string() << std::endl; // Output: John Doe
std::cout << data["address"]["street"] << std::endl; // Output: Maple Avenue
std::cout << data["skills"].size() << std::endl; // Output: 3
std::cout << data["skills"][0] << std::endl; // Output: C++
// Output: The whole object (with indent and line feed)
std::cout << json::pretty() << data << std::endl;JSON Values can be parsed from multiple sources, using multiple methods:
- Using the constructor
// Parse stream std::string json_spec = ...; Json json(Json::option_parse, json_spec);
// Parse stream std::ifstream iss("/path/to/file.json"); Json json(iss);
- Using the member function
parse// Parse string std::string json_spec = ...; Json json; json.parse(json_spec);// Parse stream std::ifstream iss("/path/to/file.json"); Json json; json.parse(iss);
- Using the namespace-level function
parse// Parse string std::string json_spec = ...; Json json = json::parse(json_spec);// Parse stream std::ifstream iss("/path/to/file.json"); Json json = json::parse(iss);
- Using the input stream extraction operator
std::istringstream iss("/path/to/file.json"); Json json; iss >> json;
- Using the member method
stringify:// Stringify to string Json json = ...; std::string json_spec = json.stringify(true); // true = pretty (with indent an line feed)
// Stringify to stream Json json = ...; json.stringify(std::cout, true); // true = pretty (with indent an line feed)
- Using the output stream insertion operator:
// Ugly (default)
Json json = ...;
std::cout << json << std::endl;// Pretty
Json json = ...;
std::cout << json::pretty() << json << std::endl;This library support JSON pointer standard as defined in RFC-6901
Example:
Json json;
json["root"]["hello"] = "world";
// Note: '~' is JSON pointer's escape character.
// The only characters that need escaping at this moment are '~' and '/'.
json["root"]["hello~world"].push_back("First");
json["root"]["hello~world"].push_back("Second");
json["root"]["hello/world"].push_back("Second First");
json["root"]["hello/world"].push_back("Second Second");
// empty string or single slash returns the same object
const Json& actual_root = json[json::Pointer("/")];
assert(&actual_root == &json);
// the nested object with key="root"
const Json& root = json[json::Pointer("/root")];
assert(&root == &json["root"]);
// Output: "world"
std::cout << json[json::Pointer("/root/hello")] << std::endl;
assert(json["root"]["hello"] == json[json::Pointer("/root/hello"));
// Note: Use '~0' to escape '~'
// Output: "First"
std::cout << json[json::Pointer("/root/hello~0world/0")] << std::endl;
assert(json["root"]["hello~world"][0] == json[json::Pointer("/root/hello~0world/0")]);
// Output: "Second"
std::cout << json[json::Pointer("/root/hello~0world/1")] << std::endl;
assert(json["root"]["hello~world"][1] == json[json::Pointer("/root/hello~0world/1")]);
// Note: Use '~1' to escape '/'
// Output: "Second First"
std::cout << json[json::Pointer("/root/hello~1world/0")] << std::endl;
// Output: "Second Second"
std::cout << json[json::Pointer("/root/hello~1world/1")] << std::endl;