Go 语言学习：Go 语言之旅 |
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官方的 Go 语言之旅 包含了一些习题，初学者应该要能够完成这些练习来巩固学习的知识点。今晚我花了几个小时做了这些习题，以给初学者作参考。这些题目我就懒得翻译了，这里给出了每个题目的中英文链接【中文应该是机器翻译的，尽量看英文】。 题目 1. 循环与函数英文题目链接 中文题目链接 2. 切片英文题目链接 中文题目链接 3. 字典英文题目链接 中文题目链接 4. 斐波那契闭包英文题目链接 中文题目链接 5. Stringers英文题目链接 中文题目链接 6. 错误英文题目链接 中文题目链接 7. Readers英文题目链接 中文题目链接 8. rot13Reader英文题目链接 中文题目链接 9. Images英文题目链接 中文题目链接 10. 相等的二叉树英文题目链接 中文题目链接 11. web 爬虫英文题目链接 中文题目链接 参考答案 1. 循环与函数 package main import ( "fmt" "math" ) func Sqrt(x float64) float64 { z0 := 1.0 z1 := z0 for { z1 -= (z0*z0 - x) / (2 * z0) if math.Abs(z0-z1) fmt.Println(Sqrt(2)) fmt.Println(math.Sqrt(2)) } 2. 切片 package main import "golang.org/x/tour/pic" func Pic(dx, dy int) [][]uint8 { s := make([][]uint8, dy) for i := range s { s[i] = make([]uint8, dx) } for x := 0; x s[x][y] = uint8((x+y)/2) } } return s } func main() { pic.Show(Pic) } 3. 字典 package main import ( "strings" "golang.org/x/tour/wc" ) func WordCount(s string) map[string]int { m := make(map[string]int) for _, word := range strings.Fields(s) { m[word] += 1 } return m } func main() { wc.Test(WordCount) } 4. 斐波那契闭包 package main import "fmt" // fibonacci is a function that returns // a function that returns an int. func fibonacci() func() int { a := -1 b := 1 return func() int { r := a + b a, b = b, a + b return r } } func main() { f := fibonacci() for i := 0; i return fmt.Sprintf("%d.%d.%d.%d", ip[0], ip[1], ip[2], ip[3]) } func main() { hosts := map[string]IPAddr{ "loopback": {127, 0, 0, 1}, "googleDNS": {8, 8, 8, 8}, } for name, ip := range hosts { fmt.Printf("%v: %v\n", name, ip) } } 6. 错误 package main import ( "math" "fmt" ) type ErrNegativeSqrt float64 func (e ErrNegativeSqrt) Error() string { return fmt.Sprint("cannot Sqrt negative number: ", float64(e)) } func Sqrt(x float64) (float64, error) { if x z1 -= (z0*z0 - x) / (2 * z0) if math.Abs(z0-z1) fmt.Println(Sqrt(2)) fmt.Println(Sqrt(-2)) } 7. Readers package main import "golang.org/x/tour/reader" type MyReader struct{} // TODO: Add a Read([]byte) (int, error) method to MyReader. func (r MyReader) Read(b []byte) (int, error) { for i := range b { b[i] = 'A' } return len(b), nil } func main() { reader.Validate(MyReader{}) } 8. rot13Reader package main import ( "io" "os" "strings" ) type rot13Reader struct { r io.Reader } func (reader rot13Reader) Read(b []byte) (int, error) { n, err := reader.r.Read(b) for i := 0; i case b[i] >= 'A' && b[i] = 'N' && b[i] = 'a' && b[i] = 'n' && b[i] s} io.Copy(os.Stdout, &r) } 9. Images package main import "image" import "image/color" import "golang.org/x/tour/pic" type Image struct { w, h int } func (img Image) ColorModel() color.Model { return color.RGBAModel } func (img Image) Bounds() image.Rectangle { return image.Rect(0, 0, img.w, img.h) } func (img Image) At(x, y int) color.Color { return color.RGBA{uint8(x), uint8(y), 255, 255} } func main() { m := Image{100, 100} pic.ShowImage(m) } 10. 相等的二叉树 package main import "fmt" import "golang.org/x/tour/tree" // Walk walks the tree t sending all values // from the tree to the channel ch. func Walk(t *tree.Tree, ch chan int) { if t == nil { return } Walk(t.Left, ch) ch v1 = fmt.Println(Same(tree.New(1), tree.New(1))) fmt.Println(Same(tree.New(1), tree.New(2))) } 11. web 爬虫 package main import ( "fmt" "sync" ) // 实现一个可在多个 goroutine 间使用的集合 type Set struct { mu sync.Mutex v map[string]bool } func (s *Set) Add(key string) { s.mu.Lock() s.v[key] = true s.mu.Unlock() } func (s *Set) Find(key string) bool { s.mu.Lock() defer s.mu.Unlock() if _, ok := s.v[key]; !ok { return false } return true } type Fetcher interface { // Fetch returns the body of URL and // a slice of URLs found on that page. Fetch(url string) (body string, urls []string, err error) } // Crawl uses fetcher to recursively crawl // pages starting with url, to a maximum of depth. func Crawl(url string, depth int, fetcher Fetcher, s *Set, quit chan int) { defer func() { quit return } body, urls, err := fetcher.Fetch(url) if err != nil { fmt.Println(err) return } fmt.Printf("found: %s %q\n", url, body) var chs []chan int for _, u := range urls { ch := make(chan int, 1) go Crawl(u, depth-1, fetcher, s, ch) chs = append(chs, ch) } for _, ch := range chs { v: make(map[string]bool)} go Crawl("https://golang.org/", 4, fetcher, s, quit) if res, ok := f[url]; ok { return res.body, res.urls, nil } return "", nil, fmt.Errorf("not found: %s", url) } // fetcher is a populated fakeFetcher. var fetcher = fakeFetcher{ "https://golang.org/": &fakeResult{ "The Go Programming Language", []string{ "https://golang.org/pkg/", "https://golang.org/cmd/", }, }, "https://golang.org/pkg/": &fakeResult{ "Packages", []string{ "https://golang.org/", "https://golang.org/cmd/", "https://golang.org/pkg/fmt/", "https://golang.org/pkg/os/", }, }, "https://golang.org/pkg/fmt/": &fakeResult{ "Package fmt", []string{ "https://golang.org/", "https://golang.org/pkg/", }, }, "https://golang.org/pkg/os/": &fakeResult{ "Package os", []string{ "https://golang.org/", "https://golang.org/pkg/", }, }, } |
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