ceph/src/jaegertracing/opentelemetry-cpp/third_party/nlohmann-json/doc/mkdocs/docs/api/basic_json/get_to.md

   1 # <small>nlohmann::basic_json::</small>get_to
   2
   3 ```cpp
   4 template<typename ValueType>
   5 ValueType& get_to(ValueType& v) const noexcept(
   6     noexcept(JSONSerializer<ValueType>::from_json(
   7         std::declval<const basic_json_t&>(), v)));
   8 ```
   9
  10 Explicit type conversion between the JSON value and a compatible value. The value is filled into the input parameter by
  11 calling the `json_serializer<ValueType>` `from_json()` method.
  12
  13 The function is equivalent to executing
  14 ```cpp
  15 ValueType v;
  16 JSONSerializer<ValueType>::from_json(*this, v);
  17 ```
  18
  19 This overload is chosen if:
  20
  21 - `ValueType` is not `basic_json`,
  22 - `json_serializer<ValueType>` has a `from_json()` method of the form `void from_json(const basic_json&, ValueType&)`
  23
  24 ## Template parameters
  25
  26 `ValueType`
  27 :   the value type to return
  28
  29 ## Return value
  30
  31 the input parameter, allowing chaining calls
  32
  33 ## Exceptions
  34
  35 Depends on what `json_serializer<ValueType>` `from_json()` method throws
  36
  37 ## Examples
  38
  39 ??? example
  40
  41     The example below shows several conversions from JSON values to other types. There a few things to note: (1)
  42     Floating-point numbers can be converted to integers, (2) A JSON array can be converted to a standard
  43     `#!cpp std::vector<short>`, (3) A JSON object can be converted to C++ associative containers such as
  44     `#cpp std::unordered_map<std::string, json>`.
  45
  46     ```cpp
  47     --8<-- "examples/get_to.cpp"
  48     ```
  49
  50     Output:
  51
  52     ```json
  53     --8<-- "examples/get_to.output"
  54     ```
  55
  56 ## Version history
  57
  58 - Since version 3.3.0.