write_at (6 of 8 overloads)

Write all of the supplied data at the specified offset before returning.

template<
    typename SyncRandomAccessWriteDevice,
    typename Allocator>
std::size_t write_at(
    SyncRandomAccessWriteDevice & d,
    uint64_t offset,
    basic_streambuf< Allocator > & b,
    boost::system::error_code & ec);

This function is used to write a certain number of bytes of data to a random access device at a specified offset. The call will block until one of the following conditions is true:

All of the data in the supplied basic_streambuf has been written.
An error occurred.

This operation is implemented in terms of zero or more calls to the device's write_some_at function.

Parameters

d: The device to which the data is to be written. The type must support the SyncRandomAccessWriteDevice concept.
offset: The offset at which the data will be written.
b: The basic_streambuf object from which data will be written.
ec: Set to indicate what error occurred, if any.

Return Value

The number of bytes transferred.

Remarks

This overload is equivalent to calling:

boost::asio::write_at(
    d, 42, b,
    boost::asio::transfer_all(), ec);