JSON for Modern C++  1.1.0
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 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 types.
1 #include <json.hpp>
2 
3 using namespace nlohmann;
4 
5 int main()
6 {
7  // create JSON values
8  json j_null;
9  json j_boolean = true;
10  json j_number_integer = 17;
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();
18  j_boolean.clear();
19  j_number_integer.clear();
20  j_number_float.clear();
21  j_object.clear();
22  j_array.clear();
23  j_string.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 }
a class to store JSON values
Definition: json.hpp:191
namespace for Niels Lohmann
Definition: json.hpp:88
void clear() noexcept
clears the contents
Definition: json.hpp:4228
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 4228 of file json.hpp.