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* ✏️ fix typos Signed-off-by: Niels Lohmann <mail@nlohmann.me> * ✏️ address review comments Signed-off-by: Niels Lohmann <mail@nlohmann.me> * ✏️ address review comments Signed-off-by: Niels Lohmann <mail@nlohmann.me> --------- Signed-off-by: Niels Lohmann <mail@nlohmann.me>
40 lines
1013 B
Markdown
40 lines
1013 B
Markdown
# <small>nlohmann::</small>ordered_json
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```cpp
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using ordered_json = basic_json<ordered_map>;
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```
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This type preserves the insertion order of object keys.
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## Iterator invalidation
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The type is based on [`ordered_map`](ordered_map.md) which in turn uses a `std::vector` to store object elements.
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Therefore, adding object elements can yield a reallocation in which case all iterators (including the
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[`end()`](basic_json/end.md) iterator) and all references to the elements are invalidated. Also, any iterator or
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reference after the insertion point will point to the same index, which is now a different value.
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## Examples
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??? example
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The example below demonstrates how `ordered_json` preserves the insertion order of object keys.
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```cpp
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--8<-- "examples/ordered_json.cpp"
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```
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Output:
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```json
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--8<-- "examples/ordered_json.output"
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```
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## See also
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- [ordered_map](ordered_map.md)
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- [Object Order](../features/object_order.md)
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## Version history
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Since version 3.9.0.
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