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 NumberFloatType = double, template< typename U > class AllocatorType = std::allocator>

nlohmann::basic_json::basic_json ( )

defaultnoexcept

Create a null JSON value. This is the implicit version of the null value constructor as it takes no parameters.

Complexity

Constant.

Requirements

This function satisfies the Container requirements:

• The complexity is constant.
• As postcondition, it holds: basic_json().empty() == true.

Example

The following code shows the constructor for a null JSON value.

#include <json.hpp>

using namespace nlohmann;

int main()
{
    // create a JSON value with default null value
    json j;

    // serialize the JSON null value
    std::cout << j << '\n';
}

Output:

null

The example code above can be translated with

g++ -std=c++11 -Isrc doc/examples/basic_json.cpp -o basic_json 

.

See also

basic_json(std::nullptr_t)