api/basic_json/meta.md

# <small>nlohmann::basic_json::</small>meta

```cpp
static basic_json meta();
```

This function returns a JSON object with information about the library, including the version number and information on
the platform and compiler.
    
## Return value

JSON object holding version information

| key         | description                                                                                                                                                                                                                                                                    |
|-------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `compiler`  | Information on the used compiler. It is an object with the following keys: `c++` (the used C++ standard), `family` (the compiler family; possible values are `clang`, `icc`, `gcc`, `ilecpp`, `msvc`, `pgcpp`, `sunpro`, and `unknown`), and `version` (the compiler version). On HP aCC compilers, `compiler` is instead the plain string `hp`. |
| `copyright` | The copyright line for the library as string.                                                                                                                                                                                                                                  |
| `name`      | The name of the library as string.                                                                                                                                                                                                                                             |
| `platform`  | The used platform as string. Possible values are `win32`, `linux`, `apple`, `unix`, and `unknown`.                                                                                                                                                                             |
| `url`       | The URL of the project as string.                                                                                                                                                                                                                                              |
| `version`   | The version of the library. It is an object with the following keys: `major`, `minor`, and `patch` as defined by [Semantic Versioning](http://semver.org), and `string` (the version string).                                                                                  |

## Exception safety

Strong guarantee: if an exception is thrown, there are no changes to any JSON value.

## Complexity

Constant.

## Examples

??? example

    The following code shows an example output of the `meta()` function.
    
    ```cpp
    --8<-- "examples/meta.cpp"
    ```
    
    Output:
    
    ```json
    --8<-- "examples/meta.output"
    ```

    Note the output is platform-dependent.

## See also

- [**NLOHMANN_JSON_VERSION_MAJOR**/**NLOHMANN_JSON_VERSION_MINOR**/**NLOHMANN_JSON_VERSION_PATCH**](../macros/nlohmann_json_version_major.md)
  \- library version information

## Version history

- Added in version 2.1.0.