On Friday, 9 September 2016 18:45:24 UTC+2, Ian Lance Taylor wrote:
>
> On Fri, Sep 9, 2016 at 7:22 AM, <vend...@gmail.com <javascript:>> wrote:
> >
> > I was trying to read a longer text from stdin, without any newline. I
> tried
> > it with many ways: fmt.Scan, bufio.NewScanner, bufio ReadLine,
> > ioutil.ReadAll. A sample code looks like this:
> >
> stackoverflow.com/questions/27196195/golang-read-from-pipe-reads-tons-of-data#answer-27196786
>
> > If the length was just a bit longer than 4096 characters, the result was
> > always the same: it was cut at 4096 characters.
> >
> > When I saved the text to a file, and read from there, every method
> worked.
> > If I changed the spaces to newlines, every method worked from stdin. So
> only
> > this combination was wrong. Looks like a bug for me.
> >
> > I wanted to use it for hackerrank.com excercises, where this is the
> typical
> > input: long line given through stdin, without newline.
> >
> > Can anyone help me please?
>
> Show us the exact code you are running, and tell us about the system
> on which you are running it.
>
> Ian
>
Almost the same code as the example I linked, I only changed the log to fmt
print, and the buffer size from 4*1024 to 8*1024. So when I run it, enter a
string with 4900 characters without newline, it waits for more input. Even
if I end it with EOF (Ctrl+d) immediately, It writes this: Bytes: 4096
Chunks: 1.
I'm on Arch linux 32 bit. Latest go:
$ go version
go version go1.7.1 linux/386
The code:
package main
import (
"bufio"
"fmt"
"io"
"os"
)
func main() {
nBytes, nChunks := int64(0), int64(0)
r := bufio.NewReader(os.Stdin)
buf := make([]byte, 0, 8*1024)
for {
n, err := r.Read(buf[:cap(buf)])
buf = buf[:n]
if n == 0 {
if err == nil {
continue
}
if err == io.EOF {
break
}
fmt.Println(err)
}
nChunks++
nBytes += int64(len(buf))
// process buf
if err != nil && err != io.EOF {
fmt.Println(err)
}
}
fmt.Println("Bytes:", nBytes, "Chunks:", nChunks)
}
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