### read_at

The `read_at` function is a composed operation that reads a certain amount of data at the specified offset before returning.

Attempt to read a certain amount of data at the specified offset before returning.

    template<
        typename SyncRandomAccessReadDevice,
        typename MutableBufferSequence>
    std::size_t read_at(
        SyncRandomAccessReadDevice & d,
        uint64_t offset,
        const MutableBufferSequence & buffers);
      » more...

    template<
        typename SyncRandomAccessReadDevice,
        typename MutableBufferSequence>
    std::size_t read_at(
        SyncRandomAccessReadDevice & d,
        uint64_t offset,
        const MutableBufferSequence & buffers,
        asio::error_code & ec);
      » more...

    template<
        typename SyncRandomAccessReadDevice,
        typename MutableBufferSequence,
        typename CompletionCondition>
    std::size_t read_at(
        SyncRandomAccessReadDevice & d,
        uint64_t offset,
        const MutableBufferSequence & buffers,
        CompletionCondition completion_condition,
        constraint_t< is_completion_condition< CompletionCondition >::value >  = 0);
      » more...

    template<
        typename SyncRandomAccessReadDevice,
        typename MutableBufferSequence,
        typename CompletionCondition>
    std::size_t read_at(
        SyncRandomAccessReadDevice & d,
        uint64_t offset,
        const MutableBufferSequence & buffers,
        CompletionCondition completion_condition,
        asio::error_code & ec,
        constraint_t< is_completion_condition< CompletionCondition >::value >  = 0);
      » more...

    template<
        typename SyncRandomAccessReadDevice,
        typename Allocator>
    std::size_t read_at(
        SyncRandomAccessReadDevice & d,
        uint64_t offset,
        basic_streambuf< Allocator > & b);
      » more...

    template<
        typename SyncRandomAccessReadDevice,
        typename Allocator>
    std::size_t read_at(
        SyncRandomAccessReadDevice & d,
        uint64_t offset,
        basic_streambuf< Allocator > & b,
        asio::error_code & ec);
      » more...

    template<
        typename SyncRandomAccessReadDevice,
        typename Allocator,
        typename CompletionCondition>
    std::size_t read_at(
        SyncRandomAccessReadDevice & d,
        uint64_t offset,
        basic_streambuf< Allocator > & b,
        CompletionCondition completion_condition,
        constraint_t< is_completion_condition< CompletionCondition >::value >  = 0);
      » more...

    template<
        typename SyncRandomAccessReadDevice,
        typename Allocator,
        typename CompletionCondition>
    std::size_t read_at(
        SyncRandomAccessReadDevice & d,
        uint64_t offset,
        basic_streambuf< Allocator > & b,
        CompletionCondition completion_condition,
        asio::error_code & ec,
        constraint_t< is_completion_condition< CompletionCondition >::value >  = 0);
      » more...

##### Requirements

Header: `asio/impl/read_at.hpp`

Convenience header: `asio.hpp`