Difference between console output stream and media file stream

php editor The difference between the console output stream and the media file stream is an important concept in program development. The console output stream is mainly used to output information during program running to the console to facilitate developers to debug and view running results. The media file stream is used to read and write media files, such as audio, video, etc. There are some differences between the two in terms of usage, data processing, and application scenarios. It is very important for developers to understand and master these differences. Next we will explore the differences and usage tips between the two in detail.

Question content

I'm having trouble trying to render a GIF in Go. The output GIF file cannot be opened using one method, but can be opened normally using another method. I found Rendering .gif in Go but it didn't solve my specific problem.

This is the code in question:

package main

import (
    "bufio"
    "fmt"
    "image"
    "image/color"
    "image/gif"
    "io"
    "math"
    "math/rand"
    "os"
    "time"
)

var palette = []color.Color{color.White, color.Black}

const (
    whiteIndex = 0
    blackIndex = 1
)

func main() {
    w := bufio.NewWriter(os.Stdout)
    lissajous(w)
}

func lissajous(out io.Writer) {
    const (
        cycles  = 5
        res     = 0.001
        size    = 100
        nframes = 64
        delay   = 8
    )
    rand.Seed(time.Now().UTC().UnixNano())

    freq := rand.Float64() * 3.0
    anim := gif.GIF{LoopCount: nframes}
    phase := 0.0

    for i := 0; i < nframes; i++ {
        rect := image.Rect(0, 0, 2 * size+1, 2 * size + 1)
        img := image.NewPaletted(rect, palette)

        for t := 0.0; t < cycles * 2 * math.Pi; t += res {
            x := math.Sin(t)
            y := math.Sin(t * freq + phase)
            img.SetColorIndex(size + int(x * size + 0.5), size + int(y * size + 0.5), blackIndex)
        }
        phase += 0.1
        anim.Delay = append(anim.Delay, delay)
        anim.Image = append(anim.Image, img)
    }
    err := gif.EncodeAll(out, &anim)
    if err != nil {
        return
    } else {
        fmt.Println(err)
    }
}

The following are the commands:

go build main.go

main > out.gif

Then, out.gif cannot be opened. However, this method works well:

func main() {
    fileName := "out.gif"
    f, err3 := os.Create(fileName)
    if err3 != nil {
        fmt.Println("create file fail")
    }
    w := bufio.NewWriter(f) 
    lissajous(w)
    w.Flush()
    f.Close()

}

I'm confused why the first method doesn't create a functional GIF file, but the second method does. Is this related to the way Go handles file writing or buffering?

Solution

According to @CeriseLimón Comments:

func main() {
    w := bufio.NewWriter(os.Stdout)
    lissajous(w)
    w.Flush()
}

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