|
◆ 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, class BinaryType = std::vector<std::uint8_t>>
void nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::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 with the current value type from type():
Value type | initial value |
null | null |
boolean | false |
string | "" |
number | 0 |
binary | An empty byte vector |
object | {} |
array | [] |
- Postcondition
- Has the same effect as calling
basic_json(const value_t v) create an empty value with a given type
constexpr value_t type() const noexcept return the type of the JSON value (explicit)
- Example
- The example below shows the effect of
clear() to different JSON types.
2 #include <nlohmann/json.hpp>
10 json j_boolean = true;
11 json j_number_integer = 17;
12 json j_number_float = 23.42;
13 json j_object = {{ "one", 1}, { "two", 2}};
14 json j_array = {1, 2, 4, 8, 16};
15 json j_string = "Hello, world";
20 j_number_integer.clear();
21 j_number_float.clear();
27 std::cout << j_null << '\n';
28 std::cout << j_boolean << '\n';
29 std::cout << j_number_integer << '\n';
30 std::cout << j_number_float << '\n';
31 std::cout << j_object << '\n';
32 std::cout << j_array << '\n';
33 std::cout << j_string << '\n';
basic_json<> json default JSON class
Output (play with this example online): null
false
0
0.0
{}
[]
""
The example code above can be translated withg++ -std=c++11 -Isingle_include doc/examples/clear.cpp -o clear
- Complexity
- Linear in the size of the JSON value.
- Iterator validity
- All iterators, pointers and references related to this container are invalidated.
- Exception safety
- No-throw guarantee: this function never throws exceptions.
- See also
- basic_json(value_t) – constructor that creates an object with the same value than calling
clear()
- Since
- version 1.0.0
Definition at line 21646 of file json.hpp.
|