pub fn copy<R, W>(reader: R, writer: &mut W) -> Copy<'_, R, W>ⓘNotable traits for Copy<'_, R, W>impl<R, W> Future for Copy<'_, R, W>where
R: AsyncRead,
W: AsyncWrite + Unpin + ?Sized, type Output = Result<u64, Error>;where
R: AsyncRead,
W: AsyncWrite + Unpin + ?Sized,Expand description
Creates a future which copies all the bytes from one object to another.
The returned future will copy all the bytes read from this AsyncRead into the
writer specified. This future will only complete once the reader has hit
EOF and all bytes have been written to and flushed from the writer
provided.
On success the number of bytes is returned.
Examples
use futures::io::{self, AsyncWriteExt, Cursor};
let reader = Cursor::new([1, 2, 3, 4]);
let mut writer = Cursor::new(vec![0u8; 5]);
let bytes = io::copy(reader, &mut writer).await?;
writer.close().await?;
assert_eq!(bytes, 4);
assert_eq!(writer.into_inner(), [1, 2, 3, 4, 0]);