....

diff --git a/learn/go/exercise/1.5.go b/learn/go/exercise/1.5.go
new file mode 100644 (file)
index 0000000..8a4df42
--- /dev/null
+++ b/learn/go/exercise/1.5.go
@@ -0,0 +1,107 @@
+/*
+ * ------------------------------------------------------------------------
+ *   File Name: 1.5.go
+ *      Author: Zhao Yanbai
+ *              2017-06-11 16:09:11 Sunday CST
+ * Description: none
+ * ------------------------------------------------------------------------
+ */
+package main
+import (
+//     "fmt"
+       "image"
+       "image/color"
+       "image/gif"
+       "io"
+       "math"
+       "math/rand"
+       "os"
+)
+
+var palette = []color.Color {
+       color.White,
+       color.Black,
+       color.RGBA{0xFF, 0x00, 0x00, 0xFF},
+       color.RGBA{0x00, 0xFF, 0x00, 0xFF},
+       color.RGBA{0x00, 0x00, 0xFF, 0xFF},
+}
+
+const (
+       lineColorIndex = 3
+)
+
+
+func lissajous(out io.Writer) {
+       const (
+               cycles          = 5
+               res                     = 0.001
+               size            = 100
+               nframes         = 128
+               delay           = 8             // 80ms
+       )
+
+       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<2*math.Pi*cycles; 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), lineColorIndex)
+               }
+               phase += 0.1
+               anim.Delay = append(anim.Delay, delay)
+               anim.Image = append(anim.Image, img)
+       }
+
+       gif.EncodeAll(out, &anim)
+}
+
+func sint(out io.Writer) {
+       const (
+               cycles          = 5
+               res                     = 0.001
+               size            = 100
+               nframes         = 24
+               delay           = 8             // 80ms
+       )
+
+       anim := gif.GIF{LoopCount: nframes}
+
+       for i := 0; i<nframes; i++ {
+               rect := image.Rect(0, 0, 2*size+1, 2*size+1)
+               img := image.NewPaletted(rect, palette)
+
+               bgn := float64(i)
+               for t := bgn; t<bgn+3.5*math.Pi; t += res {
+                       x := t
+                       y := math.Sin(t)
+                       delta := t - bgn
+                       colorIndex := uint8(1)
+                       if delta < math.Pi {
+                               colorIndex = 2
+                       } else if delta < 2*math.Pi {
+                               colorIndex = 3
+                       } else if delta < 3*math.Pi {
+                               colorIndex = 4
+                       }
+
+
+                       img.SetColorIndex(int(x*size/10.0+0.5), size+int(y*size/1.0+0.5), colorIndex)
+               }
+               anim.Delay = append(anim.Delay, delay)
+               anim.Image = append(anim.Image, img)
+       }
+
+       gif.EncodeAll(out, &anim)
+}
+
+
+func main() {
+       //defer fmt.Println("Program Exited...")
+       //lissajous(os.Stdout)
+       sint(os.Stdout)
+}

diff --git a/learn/go/exercise/1.7.go b/learn/go/exercise/1.7.go
new file mode 100644 (file)
index 0000000..089110f
--- /dev/null
+++ b/learn/go/exercise/1.7.go
@@ -0,0 +1,36 @@
+/*
+ * ------------------------------------------------------------------------
+ *   File Name: 1.7.go
+ *      Author: Zhao Yanbai
+ *              2017-06-11 17:18:40 Sunday CST
+ * Description: none
+ * ------------------------------------------------------------------------
+ */
+package main
+import (
+       "net/http"
+       "os"
+       "io"
+       "log"
+       "strings"
+)
+
+func main() {
+       for _, url := range os.Args[1:] {
+               if !strings.HasPrefix("http://", url) {
+                       url = "http://" + url
+               }
+
+               rsp, err := http.Get(url)
+               if err != nil {
+                       log.Fatalf("fetch: %s\n", err)
+               }
+
+               if n, err := io.Copy(os.Stdout, rsp.Body); err != nil {
+                       log.Fatalf("reading: %s:%s\n", url, err)
+               } else {
+                       log.Printf("\nread %d bytes. status code: %v\n", n, rsp.Status)
+               }
+       }
+
+}