JSON for Modern C++ 2.1.1
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◆ type()

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>
constexpr value_t nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer >::type ( ) const
inlineconstexprnoexcept

Return the type of the JSON value as a value from the value_t enumeration.

Returns
the type of the JSON value
Complexity\n Constant.
Exception safety\n No-throw guarantee: this member function never throws
exceptions.
Example\n The following code exemplifies type() for all JSON
types.
1#include <json.hpp>
2
3using json = nlohmann::json;
4
5int main()
6{
7 // create JSON values
9 json j_boolean = true;
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()
17 std::cout << std::boolalpha;
18 std::cout << (j_null.type() == json::value_t::null) << '\n';
19 std::cout << (j_boolean.type() == json::value_t::boolean) << '\n';
20 std::cout << (j_number_integer.type() == json::value_t::number_integer) << '\n';
21 std::cout << (j_number_float.type() == json::value_t::number_float) << '\n';
22 std::cout << (j_object.type() == json::value_t::object) << '\n';
23 std::cout << (j_array.type() == json::value_t::array) << '\n';
24 std::cout << (j_string.type() == json::value_t::string) << '\n';
25}
constexpr value_t type() const noexcept
return the type of the JSON value (explicit)
Definition json.hpp:2681
static basic_json array(std::initializer_list< basic_json > init=std::initializer_list< basic_json >())
explicitly create an array from an initializer list
Definition json.hpp:2165
static basic_json object(std::initializer_list< basic_json > init=std::initializer_list< basic_json >())
explicitly create an object from an initializer list
Definition json.hpp:2205
a class to store JSON values
Definition json.hpp:1040
basic_json<> json
default JSON class
Definition json.hpp:12369

Output (play with this example online):
true
true
true
true
true
true
true

The example code above can be translated with
g++ -std=c++11 -Isrc doc/examples/type.cpp -o type 
Since
version 1.0.0

Definition at line 2681 of file json.hpp.