Trait std::io::Seek

pub trait Seek {
    fn seek(&mut self, pos: SeekFrom) -> Result<u64>;
}

The Seek trait provides a cursor which can be moved within a stream of bytes.

The stream typically has a fixed size, allowing seeking relative to either end or the current offset.

Examples

Files implement Seek:

use std::io;
use std::io::prelude::*;
use std::fs::File;
use std::io::SeekFrom;

fn main() -> io::Result<()> {
    let mut f = File::open("foo.txt")?;

    // move the cursor 42 bytes from the start of the file
    f.seek(SeekFrom::Start(42))?;
    Ok(())
}

Required methods

fn seek(&mut self, pos: SeekFrom) -> Result<u64>

Seek to an offset, in bytes, in a stream.

A seek beyond the end of a stream is allowed, but behavior is defined by the implementation.

If the seek operation completed successfully, this method returns the new position from the start of the stream. That position can be used later with SeekFrom::Start.

Errors

Seeking to a negative offset is considered an error.

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Implementors

impl Seek for File

fn seek(&mut self, pos: SeekFrom) -> Result<u64>

impl<'_> Seek for &'_ File

fn seek(&mut self, pos: SeekFrom) -> Result<u64>

impl<R: Seek> Seek for BufReader<R>

fn seek(&mut self, pos: SeekFrom) -> Result<u64>

Seek to an offset, in bytes, in the underlying reader.

The position used for seeking with SeekFrom::Current(_) is the position the underlying reader would be at if the BufReader had no internal buffer.

Seeking always discards the internal buffer, even if the seek position would otherwise fall within it. This guarantees that calling .into_inner() immediately after a seek yields the underlying reader at the same position.

To seek without discarding the internal buffer, use BufReader::seek_relative.

See std::io::Seek for more details.

Note: In the edge case where you're seeking with SeekFrom::Current(n) where n minus the internal buffer length overflows an i64, two seeks will be performed instead of one. If the second seek returns Err, the underlying reader will be left at the same position it would have if you called seek with SeekFrom::Current(0).

impl<S: Seek + ?Sized> Seek for Box<S>

fn seek(&mut self, pos: SeekFrom) -> Result<u64>

impl<S: Seek + ?Sized, '_> Seek for &'_ mut S

fn seek(&mut self, pos: SeekFrom) -> Result<u64>

impl<T> Seek for Cursor<T> where
    T: AsRef<[u8]>, 

fn seek(&mut self, style: SeekFrom) -> Result<u64>

impl<W: Write + Seek> Seek for BufWriter<W>

fn seek(&mut self, pos: SeekFrom) -> Result<u64>

Seek to the offset, in bytes, in the underlying writer.

Seeking always writes out the internal buffer before seeking.

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