json/api/macros/json_has_cpp_11.md

JSON_HAS_CPP_11, JSON_HAS_CPP_14, JSON_HAS_CPP_17, JSON_HAS_CPP_20, JSON_HAS_CPP_23, JSON_HAS_CPP_26

#define JSON_HAS_CPP_11
#define JSON_HAS_CPP_14
#define JSON_HAS_CPP_17
#define JSON_HAS_CPP_20
#define JSON_HAS_CPP_23
#define JSON_HAS_CPP_26

The library targets C++11, but also supports some features introduced in later C++ versions (e.g., std::string_view support for C++17). For these new features, the library implements some preprocessor checks to determine the C++ standard. By defining any of these symbols, the internal check is overridden and the provided C++ version is unconditionally assumed. This can be helpful for compilers that only implement parts of the standard and would be detected incorrectly.

Default definition

The default value is detected based on preprocessor macros such as #!cpp __cplusplus, #!cpp _HAS_CXX17, or #!cpp _MSVC_LANG.

Notes

• When the C++ standard is detected automatically, #!cpp JSON_HAS_CPP_11 is always defined. When you override the detection by defining one of these macros manually, the automatic detection is skipped entirely, so you should define all applicable macros (including #!cpp JSON_HAS_CPP_11) yourself.
• All macros are undefined outside the library.

Examples

??? example

The code below forces the library to use the C++14 standard:

```cpp
#define JSON_HAS_CPP_14 1
#include <nlohmann/json.hpp>

...
```

Version history

• Added in version 3.10.5.
• Added JSON_HAS_CPP_23 in version 3.12.0.
• Added JSON_HAS_CPP_26 in version 3.12.x.