slice
package mainimport "fmt"func main() { s := make([]int, 3, 4) s[0] = 0 s[1] = 1 s[2] = 2 s1 := s[0:2] //s, s1, s2底层用的是同一个数组 s2 := s[1:4] //slice index可以超出len，但不能超出capacity，超出len的元素值为0 fmt.Println(cap(s), len(s), s) fmt.Println(s1) fmt.Println(s2) fmt.Println("*****************") s1 = append(s1, 9) //append操作导致修改了底层数组的第3个元素 fmt.Println(cap(s), len(s), s) fmt.Println(s1) fmt.Println(s2) fmt.Println("*****************") s = append(s, 7,6) //append操作导致重新分配了一个capacity相当于原先2倍的内存空间。s指向新的数组，而s1和s2还是指向老的数组 s[1] = 6 fmt.Println(cap(s), len(s), s) fmt.Println(s1) fmt.Println(s2) fmt.Println("*****************") s=append(s,s...)//可以一次append多个元素，甚至是一个slice fmt.Println(cap(s), len(s), s) fmt.Println("*****************")} 输出：
4 3 [0 1 2]
[0 1][1 2 0]*****************4 3 [0 1 9][0 1 9][1 9 0]*****************8 5 [0 6 9 7 6][0 1 9][1 9 0]*****************16 10 [0 6 9 7 6 0 6 9 7 6]*****************json
package mainimport ( "encoding/json" "fmt")type Student struct { Name string //默认情况下，序列化成json后字段名就是"Name" Class string `json:"class"` //显式指定序列化成json后字段名就是"class" Score int `json:"score,omitempty"`//omitempty表示如果该字段是空值，那在json里就不显示该字段了}func main() { stu := Student{Name: "orisun"} bytes, _ := json.Marshal(stu) str := string(bytes) fmt.Println(str) stu2 := Student{} err := json.Unmarshal(bytes, &stu2) if err != nil { panic(err) } fmt.Printf("%+v", stu2)} 输出：
{"Name":"orisun","class":""}
{Name:orisun Class: Score:0}格式化
简单的字符串格式化用 fmt.Sprint("format", value)，格式化输出用fmt.Printf("format", value)。Sprintf和Printf背后都是调的Fprintf，os.Stdout和bytes.Buffer都实现了io.Writer接口。
package fmtfunc Fprintf(w io.Writer, format string, args ...interface{}) (int, error)func Printf(format string, args ...interface{}) (int, error) { return Fprintf(os.Stdout, format, args...)}func Sprintf(format string, args ...interface{}) string { var buf bytes.Buffer Fprintf(&buf, format, args...) return buf.String()}
%d 十进制整数%x, %o, %b 十六进制，八进制，二进制整数。%f, %g, %e 浮点数： 3.141593 3.141592653589793 3.141593e+00%t 布尔：true或false%c 字符（rune） (Unicode码点)%s 字符串%q 带双引号的字符串"abc"或带单引号的字符'c'%v 变量的自然形式（natural format）%T 变量的类型%% 字面上的百分号标志（无操作数）
更复杂更高级的格式化可以用text模板或html模板。
package mainimport ( "html/template" "os")type Boy struct { Name string Id int Score float64}type Crowd struct{ TotalCount int Items []Boy}const tmplet = `{ {.TotalCount}} students
| { {.Name}} | { {.Id}} | { {.Score | printf "%.2f"}} | { {.Score | grade}} |
输出：
<h1>3 students</h1>
<table><tr style='text-align: left'>
<td>Orisun</td><td>1</td><td>56.43</td><td>fail</td></tr><tr style='text-align: left'>
<td>Tom</td><td>2</td><td>95.01</td><td>excellent</td></tr><tr style='text-align: left'>
<td>Jim</td><td>3</td><td>87.00</td><td>good</td></tr></table>
package mainimport ( "text/template" "os")type Boy struct { Name string Id int Score float64}type Crowd struct{ TotalCount int Items []Boy}const tmpl = `{ {.TotalCount}} students:{ {range .Items}}----------------------Name: { {.Name}}ID: { {.Id}}Score: { {.Score | printf "%.2f"}}Grade: { {.Score | grade}}{ {end}}`func grade(score float64) string { if score > 90 { return "excellent" } else if score > 80 { return "good" } else if score > 70 { return "general" } else if score > 60 { return "pass" } else { return "fail" }}func main() { boys := []Boy{ Boy{ "Orisun", 1, 56.4324}, Boy{ "Tom", 2, 95.009}, Boy{ "Jim", 3, 87.0}, } crowds:=Crowd{len(boys),boys} report, err := template.New("report").Funcs(template.FuncMap{ "grade": grade}).Parse(tmpl) if err != nil { panic(err) } err = report.Execute(os.Stdout, crowds) if err != nil { panic(err) }} 输出：
3 students:
----------------------
Name: OrisunID: 1Score: 56.43Grade: fail----------------------
Name: Tom
ID: 2Score: 95.01Grade: excellent----------------------
Name: JimID: 3Score: 87.00Grade: good方法接收器
package mainimport "fmt"type Man struct{ Age int}//method的receiver是非指针类型时，会产生一次拷贝func (this Man)ChangeAge1() { this.Age*=2 fmt.Println(this.Age)}//method的receiver是指针类型时，传的是内存地址，会修改原始对象的成员属性func (this *Man)ChangeAge2() { this.Age*=2 fmt.Println(this.Age)}func main() { inst:=Man{ 18} inst.ChangeAge1() fmt.Println(inst.Age) fmt.Println("**************") //不管你的method的receiver是指针类型还是非指针类型，都是可以通过指针/非指针类型进行调用的，编译器会帮你做类型转换 inst.ChangeAge2() fmt.Println(inst.Age)} 输出：
36
18**************3636BitSet
package mainimport "fmt"type BitSet struct { words []uint64}// Has reports whether the set contains the non-negative value x.func (s *BitSet) Has(x int) bool { word, bit := x/64, uint(x%64) return word < len(s.words) && s.words[word]&(1< = len(s.words) { s.words = append(s.words, 0) } s.words[word] |= 1 << bit}func main() { bitSet:=BitSet{} bitSet.Add(54334523) bitSet.Add(79878577) bitSet.Add(47989689) fmt.Println(bitSet.Has(6783729038))//false fmt.Println(bitSet.Has(47989689))//true} 快速排序
package mainimport ( "fmt" "math/rand")func swap(array []int, i int, j int) { tmp := array[j] array[j] = array[i] array[i] = tmp}func partition(array []int, left int, right int) int { pivot := array[left] i := left + 1 j := right for { for ; j > i; j-- { if array[j] < pivot { break } } for ; i < j; i++ { if array[i] > pivot { break } } if i == j { if array[i] < pivot { swap(array, i, left) return i }else{ return left } } else { swap(array, i, j) } }}func sort(array []int, left int, right int) { if left >= right { return } mid := partition(array, left, right) sort(array, left, mid-1) sort(array, mid+1, right)}func QuickSort(array []int) { sort(array, 0, len(array)-1)}func main() { array := []int{ 6, 1, 2, 7, 9, 6, 4, 5, 10, 8} QuickSort(array) for _, ele := range array { fmt.Printf("%d\t", ele) } fmt.Println() LEN := 10000 array = make([]int, LEN) for i := 0; i < LEN; i++ { array[i] = rand.Intn(LEN) } QuickSort(array) success:=true for i := 1; i < LEN; i++ { if array[i] < array[i-1] { success=false break } } fmt.Printf("success %t\n",success)}