JSON for Modern C++ 2.1.1
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◆ clear()

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>
void nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer >::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 []
Complexity\n Linear in the size of the JSON value.
Example\n The example below shows the effect of clear() to different
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 clear()
17 j_null.clear();
22 j_array.clear();
24
25 // serialize the cleared values()
26 std::cout << j_null << '\n';
27 std::cout << j_boolean << '\n';
28 std::cout << j_number_integer << '\n';
29 std::cout << j_number_float << '\n';
30 std::cout << j_object << '\n';
31 std::cout << j_array << '\n';
32 std::cout << j_string << '\n';
33}
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
void clear() noexcept
clears the contents
Definition json.hpp:5185
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):
null
false
0
0.0
{}
[]
""

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

Definition at line 5185 of file json.hpp.