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53 lines
2.1 KiB
Markdown
53 lines
2.1 KiB
Markdown
# JSON_HAS_RANGES
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```cpp
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#define JSON_HAS_RANGES /* value */
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```
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This macro indicates whether the standard library has any support for ranges. Implies support for concepts.
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Possible values are `1` when supported or `0` when unsupported.
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## Default definition
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The default value is detected based on the preprocessor macro `#!cpp __cpp_lib_ranges`.
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When the macro is not defined, the library will define it to its default value.
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!!! info "Known compiler/stdlib exclusions"
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Even when the feature-test macro `__cpp_lib_ranges` indicates ranges support is available, the library disables it on
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the following incomplete or broken toolchains:
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- **GCC 11.1.0** — disabled (the shipped `<ranges>` header has a syntax error; [issue #4440](https://github.com/nlohmann/json/issues/4440))
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- **libstdc++ < 11** — disabled (incomplete C++20 ranges support; [issue #4440](https://github.com/nlohmann/json/issues/4440))
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- **Clang < 16 with libstdc++** — disabled (incomplete ranges support; [issue #4440](https://github.com/nlohmann/json/issues/4440))
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- **libc++ < 160000** — disabled (incomplete C++20 ranges support; [issue #4440](https://github.com/nlohmann/json/issues/4440))
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- **nvcc (CUDA) 12.0.x and 12.1.x** — disabled (the `enable_borrowed_range` variable-template syntax triggers a parse error
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under these two toolkit versions; fixed in CUDA 12.2; [issue #3907](https://github.com/nlohmann/json/issues/3907))
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If `JSON_HAS_RANGES` is `0` despite `__cpp_lib_ranges` being defined, one of the exclusions above likely applies to your toolchain.
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## Examples
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??? example
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The code below forces the library to enable support for ranges:
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```cpp
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#define JSON_HAS_RANGES 1
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#include <nlohmann/json.hpp>
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...
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```
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## See also
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- [JSON_HAS_CPP_11 / JSON_HAS_CPP_14 / JSON_HAS_CPP_17 / JSON_HAS_CPP_20 / JSON_HAS_CPP_23 /
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JSON_HAS_CPP_26](json_has_cpp_11.md) - set supported C++ standard
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- [JSON_HAS_STD_FORMAT](json_has_std_format.md) - a similar feature-detection macro, for `std::format`/`std::formatter`
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support
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## Version history
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- Added in version 3.11.0.
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