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### async_read_at

The `async_read_at` function is a composed asynchronous operation that reads a certain amount of data at the specified offset.

Start an asynchronous operation to read a certain amount of data at the specified offset.

    template<
        typename AsyncRandomAccessReadDevice,
        typename MutableBufferSequence,
        typename ReadToken = default_completion_token_t<        typename AsyncRandomAccessReadDevice::executor_type>>
    DEDUCED async_read_at(
        AsyncRandomAccessReadDevice & d,
        uint64_t offset,
        const MutableBufferSequence & buffers,
        ReadToken && token = default_completion_token_t< typename AsyncRandomAccessReadDevice::executor_type >(),
        constraint_t< !is_completion_condition< ReadToken >::value >  = 0);
      » more...

    template<
        typename AsyncRandomAccessReadDevice,
        typename MutableBufferSequence,
        typename CompletionCondition,
        typename ReadToken = default_completion_token_t<        typename AsyncRandomAccessReadDevice::executor_type>>
    DEDUCED async_read_at(
        AsyncRandomAccessReadDevice & d,
        uint64_t offset,
        const MutableBufferSequence & buffers,
        CompletionCondition completion_condition,
        ReadToken && token = default_completion_token_t< typename AsyncRandomAccessReadDevice::executor_type >(),
        constraint_t< is_completion_condition< CompletionCondition >::value >  = 0);
      » more...

    template<
        typename AsyncRandomAccessReadDevice,
        typename Allocator,
        typename ReadToken = default_completion_token_t<        typename AsyncRandomAccessReadDevice::executor_type>>
    DEDUCED async_read_at(
        AsyncRandomAccessReadDevice & d,
        uint64_t offset,
        basic_streambuf< Allocator > & b,
        ReadToken && token = default_completion_token_t< typename AsyncRandomAccessReadDevice::executor_type >(),
        constraint_t< !is_completion_condition< ReadToken >::value >  = 0);
      » more...

    template<
        typename AsyncRandomAccessReadDevice,
        typename Allocator,
        typename CompletionCondition,
        typename ReadToken = default_completion_token_t<        typename AsyncRandomAccessReadDevice::executor_type>>
    DEDUCED async_read_at(
        AsyncRandomAccessReadDevice & d,
        uint64_t offset,
        basic_streambuf< Allocator > & b,
        CompletionCondition completion_condition,
        ReadToken && token = default_completion_token_t< typename AsyncRandomAccessReadDevice::executor_type >(),
        constraint_t< is_completion_condition< CompletionCondition >::value >  = 0);
      » more...

##### Requirements

Header: `boost/asio/read_at.hpp`

Convenience header: `boost/asio.hpp`