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>

void nlohmann::basic_json::clear ( )

inlinenoexcept

Clears the content of a JSON value and resets it to the default value as if basic_json(value_t) would have been called:

Value type	initial value
null	null
boolean	false
string	""
number	0
object	{}
array	[]

Note

Floating-point numbers are set to 0.0 which will be serialized to 0. The vale type remains number_float_t.

Complexity

Linear in the size of the JSON value.

Example

The example below shows the effect of clear to different JSON value types.

#include <json.hpp>

using namespace nlohmann;

int main()
{
    // create JSON values
    json j_null;
    json j_boolean = true;
    json j_number_integer = 17;
    json j_number_float = 23.42;
    json j_object = {{"one", 1}, {"two", 2}};
    json j_array = {1, 2, 4, 8, 16};
    json j_string = "Hello, world";

    // call clear()
    j_null.clear();
    j_boolean.clear();
    j_number_integer.clear();
    j_number_float.clear();
    j_object.clear();
    j_array.clear();
    j_string.clear();

    // serialize the cleared values()
    std::cout << j_null << '\n';
    std::cout << j_boolean << '\n';
    std::cout << j_number_integer << '\n';
    std::cout << j_number_float << '\n';
    std::cout << j_object << '\n';
    std::cout << j_array << '\n';
    std::cout << j_string << '\n';
}

Output:

null
false
0
0
{}
[]
""

The example code above can be translated with

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

.