# 1.0.0[−][src]Function std::io::copy

    pub fn copy<R: ?Sized, W: ?Sized>(reader: &mut R, writer: &mut W) -> Result<u64> where
        R: Read,
        W: Write,

Copies the entire contents of a reader into a writer.

This function will continuously read data from `reader` and then write it into `writer` in a streaming fashion until `reader` returns EOF.

On success, the total number of bytes that were copied from `reader` to `writer` is returned.

If you’re wanting to copy the contents of one file to another and you’re working with filesystem paths, see the `fs::copy` function.

# Errors

This function will return an error immediately if any call to `read` or `write` returns an error. All instances of `ErrorKind::Interrupted` are handled by this function and the underlying operation is retried.

# Examples

    use std::io;

    fn main() -> io::Result<()> {
        let mut reader: &[u8] = b"hello";
        let mut writer: Vec<u8> = vec![];

        io::copy(&mut reader, &mut writer)?;

        assert_eq!(&b"hello"[..], &writer[..]);
        Ok(())
    }Run

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