JSON for Modern C++  2.0.0
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 = int64_t, class NumberUnsignedType = uint64_t, class NumberFloatType = double, template< typename U > class AllocatorType = std::allocator>
bool operator== ( const_reference  v,
std::nullptr_t   
)
friend

The functions compares the given JSON value against a null pointer. As the null pointer can be used to initialize a JSON value to null, a comparison of JSON value v with a null pointer should be equivalent to call v.is_null().

Parameters
[in]vJSON value to consider
Returns
whether v is null
Complexity
Constant.
Example
The example compares several JSON types to the null pointer.
1 #include <json.hpp>
2 
3 using json = nlohmann::json;
4 
5 int main()
6 {
7  // create several JSON values
8  json array = {1, 2, 3};
9  json object = {{"A", "a"}, {"B", "b"}};
10  json number = 17;
11  json string = "foo";
12  json null;
13 
14  // output values and comparisons
15  std::cout << std::boolalpha;
16  std::cout << array << " == nullptr " << (array == nullptr) << '\n';
17  std::cout << object << " == nullptr " << (object == nullptr) << '\n';
18  std::cout << number << " == nullptr " << (number == nullptr) << '\n';
19  std::cout << string << " == nullptr " << (string == nullptr) << '\n';
20  std::cout << null << " == nullptr " << (null == nullptr) << '\n';
21 }
basic_json<> json
default JSON class
Definition: json.hpp:8653

Output (play with this example online):

[1,2,3] == nullptr false
{"A":"a","B":"b"} == nullptr false
17 == nullptr false
"foo" == nullptr false
null == nullptr true

The example code above can be translated with

g++ -std=c++11 -Isrc doc/examples/operator__equal__nullptr_t.cpp -o operator__equal__nullptr_t 
Since
version 1.0.0

Definition at line 5290 of file json.hpp.