Go: Skip bytes from a stream using io.reader

Question

What is the best way in Go to skip forward a number of bytes in a stream using io.Reader? That is, is there a function in the standard library which takes a reader and a count that will read and dispose count bytes from the reader?

Example use case:

func DoWithReader(r io.Reader) {      
    SkipNBytes(r, 30);     // Read and dispose 30 bytes from reader
}

I don't need to go backwards in the stream so anything that can work without converting io.Reader to another reader type would be preferred.

Answer 1

You could use this construction:

import "io"
import "io/ioutil"

io.CopyN(ioutil.Discard, yourReader, count)

It copies the requested amount of bytes into an io.Writer that discards what it reads.

If your io.Reader is an io.Seeker, you might want to consider seeking in the stream to skip the amount of bytes you want to skip:

import "io"
import "io/ioutil"

switch r := yourReader.(type) {
case io.Seeker:
    r.Seek(count, io.SeekCurrent)
default:
    io.CopyN(ioutil.Discard, r, count)
}