# JSON_SKIP_LIBRARY_VERSION_CHECK

```
#define JSON_SKIP_LIBRARY_VERSION_CHECK
```

When defined, the library will not create a compiler warning when a different version of the library was already included.

## Default definition

By default, the macro is not defined.

```
#undef JSON_SKIP_LIBRARY_VERSION_CHECK
```

## Notes

ABI compatibility

Mixing different library versions in the same code can be a problem as the different versions may not be ABI compatible.

## Examples

Example: switch off the version check

The code below switches off the warning about including a different version of the library.

```
#define JSON_SKIP_LIBRARY_VERSION_CHECK 1
#include <nlohmann/json.hpp>

...
```

Example: warning about a different library version

The following warning will be shown in case a different version of the library was already included:

```
Already included a different version of the library!
```

## See also

- [NLOHMANN_JSON_VERSION_MAJOR, NLOHMANN_JSON_VERSION_MINOR, NLOHMANN_JSON_VERSION_PATCH](https://json.nlohmann.me/api/macros/nlohmann_json_version_major/index.md) - library version information

## Version history

- Added in version 3.11.0.