JSON for Modern C++  2.1.1

◆ type_name()

template<template< typename U, typename V, typename... Args > class ObjectType = std::map, template< typename U, typename... Args > class ArrayType = std::vector, class StringType = std::string, class BooleanType = bool, class NumberIntegerType = std::int64_t, class NumberUnsignedType = std::uint64_t, class NumberFloatType = double, template< typename U > class AllocatorType = std::allocator, template< typename T, typename SFINAE=void > class JSONSerializer = adl_serializer>
std::string nlohmann::basic_json::type_name ( ) const
inline

Returns the type name as string to be used in error messages - usually to indicate that a function was called on a wrong JSON type.

Returns
basically a string representation of a the m_type member
Complexity
Constant.
Example
The following code exemplifies type_name() for all JSON types.
1 #include <json.hpp>
2 
3 using json = nlohmann::json;
4 
5 int main()
6 {
7  // create JSON values
8  json j_null;
9  json j_boolean = true;
10  json j_number_integer = 17;
11  json j_number_float = 23.42;
12  json j_object = {{"one", 1}, {"two", 2}};
13  json j_array = {1, 2, 4, 8, 16};
14  json j_string = "Hello, world";
15 
16  // call type_name()
17  std::cout << j_null.type_name() << '\n';
18  std::cout << j_boolean.type_name() << '\n';
19  std::cout << j_number_integer.type_name() << '\n';
20  std::cout << j_number_float.type_name() << '\n';
21  std::cout << j_object.type_name() << '\n';
22  std::cout << j_array.type_name() << '\n';
23  std::cout << j_string.type_name() << '\n';
24 }
basic_json<> json
default JSON class
Definition: json.hpp:12369
Output (play with this example online):
null
boolean
number
number
object
array
string
The example code above can be translated with
g++ -std=c++11 -Isrc doc/examples/type_name.cpp -o type_name 
Since
version 1.0.0, public since 2.1.0

Definition at line 8065 of file json.hpp.