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Niels Lohmann
52b72b5684
- Make the iterator range illustrations legible in dark mode (prefers-color-scheme rules inside the SVGs). - Add a "Byte layout" section with a color-coded byte table to each binary format page (BJData, BON8, BSON, CBOR, MessagePack, UBJSON), and highlight the smallest size per file in the comparison table. - Add "See also" sections to the overview pages that lacked one. - Split the release notes into one page per release, grouped by minor version on the overview page, with an "API changes" section per release generated from the API pages' version histories (hooks/api_changes.py). - Fact-check the release notes and version histories against the release tags and correct wrong or misleading entries (e.g., json_serializer 2.1.0, merge_patch 3.1.0, items, count, operator[], to_bjdata, std::string_view key support). Signed-off-by: Niels Lohmann <mail@nlohmann.me>
1.4 KiB
1.4 KiB
Element Access
There are many ways elements in a JSON value can be accessed:
- unchecked access via
operator[] - checked access via
at - access with default value via
value - iterators
- JSON pointers
Testing whether a key or index exists before accessing it is also possible, with
contains or find (which returns an iterator to
the value, or end() if it is not found).
flowchart TD
A["accessing a value"] --> B{"must it exist?"}
B -->|"yes, missing is an error"| C["at() -- throws"]
B -->|"yes, but checking is my job"| D["operator[] -- unchecked"]
B -->|"no, a fallback is fine"| E["value() -- default value"]
A --> F{"just testing first?"}
F -->|"yes"| G["contains() / find()"]