json/doc/mkdocs/docs/api/basic_json/is_discarded.md

basic_json::is_discarded

constexpr bool is_discarded() const noexcept;

This function returns true if and only if the JSON value was discarded during parsing with a callback function (see parser_callback_t).

Return value

#!cpp true if type is discarded, #!cpp false otherwise.

Exception safety

No-throw guarantee: this member function never throws exceptions.

Complexity

Constant.

Notes

This function will always be #!cpp false for JSON values after parsing. That is, discarded values can only occur during parsing, but will be removed when inside a structured value or replaced by null in other cases.

Example

??? example

The following code exemplifies `is_discarded()` for all JSON types.

```cpp
--8<-- "examples/is_discarded.cpp"
```

Output:

```json
--8<-- "examples/is_discarded.output"
```

Version history

• Added in version 1.0.0.