# nlohmann::basic_json::empty
```cpp
bool empty() const noexcept;
```
Checks if a JSON value has no elements (i.e., whether its [`size()`](size.md) is `0`).
## Return value
The return value depends on the different types and is defined as follows:
| Value type | return value |
|------------|----------------------------------------|
| null | `#!cpp true` |
| boolean | `#!cpp false` |
| string | `#!cpp false` |
| number | `#!cpp false` |
| binary | `#!cpp false` |
| object | result of function `object_t::empty()` |
| array | result of function `array_t::empty()` |
## Exception safety
No-throw guarantee: this function never throws exceptions.
## Complexity
Constant, as long as [`array_t`](array_t.md) and [`object_t`](object_t.md) satisfy the
[Container](https://en.cppreference.com/w/cpp/named_req/Container) concept; that is, their `empty()` functions have
constant complexity.
## Possible implementation
```cpp
bool empty() const noexcept
{
return size() == 0;
}
```
## Notes
This function does not return whether a string stored as JSON value is empty -- it returns whether the JSON container
itself is empty which is `#!cpp false` in the case of a string.
## Examples
??? example
The following code uses `empty()` to check if a JSON object contains any elements.
```cpp
--8<-- "examples/empty.cpp"
```
Output:
```json
--8<-- "examples/empty.output"
```
## Version history
- Added in version 1.0.0.
- Extended to return `#!cpp false` for binary types in version 3.8.0.