Запустите асинхронную операцию для считывания определенного количества данных из потока.
template<
    typename AsyncReadStream,
    typename MutableBufferSequence,
    typename ReadHandler>
void-or-deduced async_read(
    AsyncReadStream & s,
    const MutableBufferSequence & buffers,
    ReadHandler handler);
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template<
    typename AsyncReadStream,
    typename MutableBufferSequence,
    typename CompletionCondition,
    typename ReadHandler>
void-or-deduced async_read(
    AsyncReadStream & s,
    const MutableBufferSequence & buffers,
    CompletionCondition completion_condition,
    ReadHandler handler);
  » more...
template<
    typename AsyncReadStream,
    typename Allocator,
    typename ReadHandler>
void-or-deduced async_read(
    AsyncReadStream & s,
    basic_streambuf< Allocator > & b,
    ReadHandler handler);
  » more...
template<
    typename AsyncReadStream,
    typename Allocator,
    typename CompletionCondition,
    typename ReadHandler>
void-or-deduced async_read(
    AsyncReadStream & s,
    basic_streambuf< Allocator > & b,
    CompletionCondition completion_condition,
    ReadHandler handler);
  » more...
 Руководитель: boost/asio/read.hpp<5
Удобный заголовок: boost/asio.hpp<5