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nlohmann
82 lines
4.1 KiB
Markdown
82 lines
4.1 KiB
Markdown
# nlohmann::basic_json::meta
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```
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static basic_json meta();
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```
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This function returns a JSON object with information about the library, including the version number and information on the platform and compiler.
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## Return value
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JSON object holding version information
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| key | description |
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| ----------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
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| `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`. |
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| `copyright` | The copyright line for the library as string. |
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| `name` | The name of the library as string. |
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| `platform` | The used platform as string. Possible values are `win32`, `linux`, `apple`, `unix`, and `unknown`. |
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| `url` | The URL of the project as string. |
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| `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). |
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## Exception safety
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Strong guarantee: if an exception is thrown, there are no changes to any JSON value.
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## Complexity
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Constant.
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## Examples
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Example
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The following code shows an example output of the `meta()` function.
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```
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#include <iostream>
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#include <iomanip>
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#include <nlohmann/json.hpp>
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using json = nlohmann::json;
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int main()
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{
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// call meta()
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std::cout << std::setw(4) << json::meta() << '\n';
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}
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```
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Output:
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```
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{
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"compiler": {
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"c++": "201103",
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"family": "gcc",
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"version": "12.4.0"
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},
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"copyright": "(C) 2013-2026 Niels Lohmann",
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"name": "JSON for Modern C++",
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"platform": "apple",
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"url": "https://github.com/nlohmann/json",
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"version": {
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"major": 3,
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"minor": 12,
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"patch": 0,
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"string": "3.12.0"
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}
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}
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```
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Note the output is platform-dependent.
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## See also
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- [**NLOHMANN_JSON_VERSION_MAJOR**/**NLOHMANN_JSON_VERSION_MINOR**/**NLOHMANN_JSON_VERSION_PATCH**](https://json.nlohmann.me/api/macros/nlohmann_json_version_major/index.md)
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- library version information
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## Version history
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- Added in version 2.1.0.
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