golang notes(2)golangmoocdabs的博客-

1, IDE (goland)

One may need ‘jetbrains-agent-latest.zip‘: 

链接: https://pan.baidu.com/s/1Ze1TUhByRNX7BkAU8mNpIw 提取码: dx2k

2, defer

<Defer, Panic, and Recover> is an excellent doc:  https://www.cnblogs.com/kaid/p/9698477.html

3, Execise: Slices

 package main  import (  //"fmt"  "golang.org/x/tour/pic" )  func Pic(dx, dy int) [][]uint8 {  var p [][]uint8 = make([][]uint8, dx)   for i := 0; i < dx; i++ {   p[i] = make([]uint8, dy)   for j :=0; j < dy; j++ {    p[i][j] = uint8(i*j)   }  }   return p }  func main() {     //fmt.Println(Pic(16, 16))     pic.Show(Pic) }

The result output looks like:

 IMAGE:iVBORw0KGgoAAAANSUhEUgAAAQAAAAEACAIAAADTED8xAACAAElEQVR42uy9B3jUVfb/P7r21dVVdy1r74o1o //omitted 348mQMB8NVXuvpRP57MgQD4+mtd/agfT+ZAAPz1r7r6UT+ezIEA+OYbXf2oH0/mQAD87W+6+lE/nsyBAPj2W139qB9P5kAAfPedrn7UjydzIADu3dPVj/rxZI7/HwAA//9vd4RSMvSyIgAAAABJRU5ErkJggg== 

From here(https://stackoverflow.com/questions/18553246/tour-golang-org36-the-functionality-implemented-by-pic-show), we can see the implementation of pic.Show:

Funny thing is it ends up printing the string “IMAGE:” followed by the base64 encoded string. Seems that play.golang.org parses the output converting this to an img tag. Try the following example: https://play.golang.org/p/RZPqp164eS 

Since the program needs import a 3rd-party package: golang.org/x/tour/pic, make sure to create a go.mod first:

 (07:30 dabs@CNU1343VF8 slices) > ls go.mod  slices  slices.go  (07:30 dabs@CNU1343VF8 slices) > cat go.mod module slices  (07:30 dabs@CNU1343VF8 slices) > go build slices.go go: finding module for package golang.org/x/tour/pic go: found golang.org/x/tour/pic in golang.org/x/tour v0.0.0-20200508155540-0608babe047d 

4, Execise: Maps

 package  main  import (  //"fmt"  "strings"  "golang.org/x/tour/wc" )  func main() {  wc.Test(WordCount) }  func WordCount(s string) map[string]int {  m := make(map[string]int)  tokens := strings.Fields(s)  for _, word := range tokens {   v, ok := m[word]   if ok {    m[word] = v + 1   } else {    m[word] = 1   }  }   return m } 

Output looks like:

 PASS  f("I am learning Go!") =    map[string]int{"Go!":1, "I":1, "am":1, "learning":1} PASS  f("The quick brown fox jumped over the lazy dog.") =    map[string]int{"The":1, "brown":1, "dog.":1, "fox":1, "jumped":1, "lazy":1, "over":1, "quick":1, "the":1} PASS  f("I ate a donut. Then I ate another donut.") =    map[string]int{"I":2, "Then":1, "a":1, "another":1, "ate":2, "donut.":2} PASS  f("A man a plan a canal panama.") =    map[string]int{"A":1, "a":2, "canal":1, "man":1, "panama.":1, "plan":1} 

5, Execise: Fibonacci closures

 package main  import (  "fmt" )  func main() {  f := fibonacci()  for i := 0; i < 10; i++ {   fmt.Println(f())  } }  func fibonacci() func() int {  var fibs []int  return func() int {   var v int   i := len(fibs)   switch {   case i == 0 || i == 1:    v = 1    fibs = append(fibs, v)   default:    v = fibs[i-1] + fibs[i-2]    fibs = append(fibs, v)   }    return v  } }

Output looks like:

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