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A tour of Go
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| // 25. Exercise: Loops and Functions | |
| package main | |
| import ( | |
| "fmt" | |
| "math" | |
| ) | |
| func Sqrt(x float64) float64 { | |
| z := float64(1) | |
| y := float64(0) | |
| for { | |
| z = z-(z*z-x)/(2*z) | |
| if math.Abs(z-y) < 1e-15 { | |
| return y | |
| } | |
| y = z | |
| } | |
| } | |
| func main() { | |
| fmt.Println(Sqrt(2)) | |
| fmt.Println(math.Sqrt(2)) | |
| } | |
| // 38. Exercise: Slices | |
| package main | |
| import ( | |
| "code.google.com/p/go-tour/pic" | |
| ) | |
| func Pic(dx, dy int) [][]uint8 { | |
| result := make([][]uint8, dy); | |
| for x := 0; x < dy; x++ { | |
| result[x] = make([]uint8, dx); | |
| for y := 0; y < dx; y++ { | |
| result[x][y] = uint8(x^y); | |
| //result[x][y] = uint8((x+y)/2); | |
| //result[x][y] = uint8(x*y); | |
| } | |
| } | |
| return result; | |
| } | |
| func main() { | |
| pic.Show(Pic) | |
| } | |
| // 43. Exercise: Maps | |
| package main | |
| import ( | |
| "strings" | |
| "code.google.com/p/go-tour/wc" | |
| ) | |
| func WordCount(s string) map[string]int { | |
| m := make(map[string]int) | |
| a := strings.Fields(s) | |
| n := len(a) | |
| for i := 0; i < n; i++ { | |
| (m[a[i]])++ | |
| } | |
| return m | |
| } | |
| func main() { | |
| wc.Test(WordCount) | |
| } | |
| // 46. Exercise: Fibonacci closure | |
| package main | |
| import "fmt" | |
| // fibonacci is a function that returns | |
| // a function that returns an int. | |
| func fibonacci() func() int { | |
| m := 0 | |
| n := 1 | |
| return func() int { | |
| m, n = n, m+n | |
| return m | |
| } | |
| } | |
| func main() { | |
| f := fibonacci() | |
| for i := 0; i < 10; i++ { | |
| fmt.Println(f()) | |
| } | |
| } | |
| // 50. Advanced Exercise: Complex cube roots |
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