33 lines
1.4 KiB
Markdown
33 lines
1.4 KiB
Markdown
# Element Access
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There are many ways elements in a JSON value can be accessed:
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- unchecked access via [`operator[]`](unchecked_access.md)
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- checked access via [`at`](checked_access.md)
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- access with default value via [`value`](default_value.md)
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- [iterators](../iterators.md)
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- [JSON pointers](../json_pointer.md)
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Testing whether a key or index exists before accessing it is also possible, with
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[`contains`](../../api/basic_json/contains.md) or [`find`](../../api/basic_json/find.md) (which returns an iterator to
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the value, or `end()` if it is not found).
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```mermaid
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flowchart TD
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A["accessing a value"] --> B{"must it exist?"}
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B -->|"yes, missing is an error"| C["at() -- throws"]
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B -->|"yes, but checking is my job"| D["operator[] -- unchecked"]
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B -->|"no, a fallback is fine"| E["value() -- default value"]
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A --> F{"just testing first?"}
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F -->|"yes"| G["contains() / find()"]
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```
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## See also
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- [**operator[]**](../../api/basic_json/operator%5B%5D.md) - unchecked access
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- [**at**](../../api/basic_json/at.md) - checked access
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- [**value**](../../api/basic_json/value.md) - access with default value
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- [**contains**](../../api/basic_json/contains.md) and [**find**](../../api/basic_json/find.md) - test for existence
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- [**front**](../../api/basic_json/front.md) and [**back**](../../api/basic_json/back.md) - first and last element
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- [**items**](../../api/basic_json/items.md) - iterate over keys and values
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