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# nlohmann::basic_json::clear

    void clear() noexcept;

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 | `[]`

Has the same effect as calling

    *this = basic_json(type());

## Exception safety

No-throw guarantee: this function never throws exceptions.

## Complexity

Linear in the size of the JSON value.

## Notes

All iterators, pointers and references related to this container are invalidated.

## Examples

Example

The example below shows the effect of `clear()` to different JSON types.

    #include <iostream>
    #include <nlohmann/json.hpp>

    using json = nlohmann::json;

    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
    0.0
    {}
    []
    ""

## Version history

- Added in version 1.0.0.
- Added support for binary types in version 3.8.0.

Last update: May 1, 2022
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