json/Reference.md

Reference

Types and default values

JSON type	value_type	C++ type	type alias	default value
null	value_type::null	nullptr_t	-	nullptr
string	value_type::string	std::string	JSON::string_t	""
number (integer)	value_type::number	int	JSON::number_t	0
number (floating point)	value_type::number_float	double	JSON::number_float_t	0.0
array	value_type::array	std::array<JSON>	JSON::array_t	{}
object	value_type::object	std::map<std::string, JSON>	JSON::object_t	{}

Type conversions

There are only a few type conversions possible:

• An integer number can be translated to a floating point number.
• A floating point number can be translated to an integer number. Note the number is truncated and not rounded, ceiled or floored.
• Any value (i.e., boolean, string, number, null) but JSON objects can be translated into an array. The result is a singleton array that consists of the value before.
• Any other conversion will throw a std::logic_error exception.

When compatible, JSON values implicitly convert to std::string, int, double, JSON::array_t, and JSON::object_t. Furthermore, explicit type conversion is possible using the get<>() function with the aforementioned types.

Initialization

JSON values can be created from many literals and variable types:

JSON type	literal/variable types	examples
none	null pointer literal, nullptr_t type, no value	nullptr
boolean	boolean literals, bool type, JSON::boolean_t type	true, false
string	string literal, char* type, std::string type, std::string&& rvalue reference, JSON::string_t type	"Hello"
number (integer)	integer literal, short int type, int type, JSON_number_t type	42
number (floating point)	floating point literal, float type, double type, JSON::number_float_t type	3.141529
array	initializer list whose elements are JSON values (or can be translated into JSON values using the rules above), std::vector<JSON> type, JSON::array_t type, JSON::array_t&& rvalue reference	{1, 2, 3, true, "foo"}
object	initializer list whose elements are pairs of a string literal and a JSON value (or can be translated into JSON values using the rules above), std::map<std::string, JSON> type, JSON::object_t type, JSON::object_t&& rvalue reference	{ {"key1", 42}, {"key2", false} }