api/json_pointer/empty/index.md

# nlohmann::json_pointer::empty

```
bool empty() const noexcept;
```

Return whether the pointer points to the root document.

## Return value

`true` iff the JSON pointer points to the root document.

## Exception safety

No-throw guarantee: this function never throws exceptions.

## Complexity

Constant.

## Examples

Example

The example shows the result of `empty` for different JSON Pointers.

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

using json = nlohmann::json;

int main()
{
    // different JSON Pointers
    json::json_pointer ptr0;
    json::json_pointer ptr1("");
    json::json_pointer ptr2("/foo");
    json::json_pointer ptr3("/foo/0");

    // call empty()
    std::cout << std::boolalpha
              << "\"" << ptr0 << "\": " << ptr0.empty() << '\n'
              << "\"" << ptr1 << "\": " << ptr1.empty() << '\n'
              << "\"" << ptr2 << "\": " << ptr2.empty() << '\n'
              << "\"" << ptr3 << "\": " << ptr3.empty() << std::endl;
}
```

Output:

```
"": true
"": true
"/foo": false
"/foo/0": false
```

## Version history

Added in version 3.6.0.