Json.at

// 1
Json& at(const Str& key);

// 2
const Json& at(const Str& key) const;

// 3
Json& at(const std::size_t index);

// 4
const Json& at(const std::size_t index) const;

1. Accesses object member by key - returns mutable reference, throws on invalid key
2. Accesses object member by key - returns const reference, throws on invalid key
3. Accesses array element by index - returns mutable reference, throws on out-of-bounds
4. Accesses array element by index - returns const reference, throws on out-of-bounds

Exception Safety - Throws std::bad_variant_access if underlying data isn't Obj/Arr - Throws std::out_of_range for invalid keys/indices

Complexity - Arr access: O(1) - Obj access: O(logN) (ordered map) / amortized O(1) (hash map)

Version

Since v3.0.0 .