json/api/basic_json/clear.md

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 with no subtype
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.

```cpp
--8<-- "examples/clear.cpp"
```

Output:

```json
--8<-- "examples/clear.output"
```

See also

• erase removes elements from a JSON value
• empty checks whether the JSON value has no elements

Version history

• Added in version 1.0.0.
• Added support for binary types in version 3.8.0.
• Fixed in version 3.13.0 to also clear the subtype of a binary value; before, the subtype was left unchanged.