Tuple-like element access.

Synopsis

Defined in header <boost/json/value.hpp>

template<
    std::size_t I,
    class T>
see-below
get(
    T&& kvp);

Description

This overload permits the key and value of a key_value_pair to be accessed by index. For example:

[link json.ref.boost__json__key_value_pair `key_value_pair`] kvp( "num" , 42);

[link json.ref.boost__json__string_view `string_view`] key = get<0>(kvp);
[link json.ref.boost__json__value `value`]& jv = get<1>(kvp);

Structured Bindings

When using C++17 or greater, objects of type key_value_pair may be used to initialize structured bindings:

[link json.ref.boost__json__key_value_pair `key_value_pair`] kvp( "num" , 42);

auto & [key, [link json.ref.boost__json__value `value`]] = kvp;

Depending on the value of I, the return type will be:

Any other value for I is ill-formed.

Template Parameters

Constraints

std::is_same_v< std::remove_cvref_t<T>, key_value_pair >

Return Value

kvp.key() if I == 0, or kvp.value() if I == 1.

Parameters

Convenience header <boost/json.hpp>