【Go自学版】01-基础

// 变量
var a, b, c = 8, 2.3, "hello"
var d float64;
e := 6var A []int;
var B [10]int;
C := [10]int{1, 2, 3, 4}
for i := 0; i < len(B); i ++ {}
for _, value := range C {}
D = make([]int, 3)
// len = 4, cap = 10, 扩容方式 cap*=2
E := make([]int, 4, 10)
E = append(E, 1)
E1 := E[0:2] // 浅拷贝，公用底层
E2 := make([]int, 3) 
copy(E2, E) // 深拷贝
E1[0] = 100 // E会改变，E2不会改变

// 导包方式
import (new_name "package_name1""package_name2". "package_name3"
)// typedef
type myint int

// map
var mp map[string]string
if mp == nil {fmt.Printf("空\n")}
mp = make(map[string]int, 10)
mp["one"] = 1
mp["two"] = 2cMap := make(map[string]string)
cMap["one"] = "1"
cMap["two"] = "22"
delete(cMap, "one")
cMap["two"] = "2"

// 析构函数, stack
func main() {defer fmt.Printf("defer 1\n")defer fmt.Printf("defer 2\n")
}

// 函数名开头小写表示私有,大写表示公有
func funName1() {}
func FunName2(a int, b string) (int, string) {ans := avar s string = breturn ans, s
}

// 本质是一个指针
type AnimalIF interface {Eat()Sleep()GetName() string
}type Dog struct {name string
}func (this *Dog) Eat() {fmt.Printf("Dog eat\n")
}func (this *Dog) Sleep() {fmt.Printf("Dog sleep\n")
}func (this *Dog) GetName() string {return this.name
}type Cat struct {name string
}func (this *Cat) Eat() {fmt.Printf("Cat eat\n")
}func (this *Cat) Sleep() {fmt.Printf("Cat sleep\n")
}func (this *Cat) GetName() string {return this.name
}func main() {var animal AnimalIFanimal = &Cat{"mike"}animal.Eat()animal.Sleep()dog := Dog{"jack"}fmt.Println(dog.GetName())
}

func testInterface(x interface{}) {value, f := x.(string)if f {fmt.Printf("value is %s", value)fmt.Printf("type is string")} else {fmt.Printf("type is not string")}
}

// [type, value]
type User struct {Id   intName string
}func (this User) Call() {fmt.Printf("user is called\n")fmt.Printf("%v\n", this)
}func reflectVar(x interface{}) {xValue := reflect.ValueOf(x)xType := reflect.TypeOf(x)fmt.Println(xType, xValue)for i := 0; i < xType.NumField(); i++ {field := xType.Field(i)value := xValue.Field(i).Interface()fmt.Printf("%s: %v = %v\n", field.Name, field.Type, value)}for i := 0; i < xType.NumMethod(); i++ {m := xType.Method(i)fmt.Printf("%s: %v\n", m.Name, m.Type)}
}func main() {user := User{11, "mike"}reflectVar(user)
}

// 标签
type User struct {Id   int    `info:"id" doc:"编号"`Name string `info:"name" doc:"姓名"`
}func FindTag(x interface{}) {// 传指针 FindTag(&user)t := reflect.TypeOf(x).Elem()// 传值 FindTag(user)//t := reflect.TypeOf(x)for i := 0; i < t.NumField(); i++ {tagString := t.Field(i).Tag.Get("info")docString := t.Field(i).Tag.Get("doc")fmt.Println("info: ", tagString, ",", "doc: ", docString)}
}// json
type Moive struct {// 变量开头大写且加tag才能进jsonTitle  string   `json:"title"`Year   int      `json:"year"`Price  float64  `json:"price"`Actors []string `json:"actors"`
}func ReadJson(movie interface{}) {jsonStr, err := json.Marshal(movie)if err != nil {fmt.Printf("json marshal error %v\n", err)} else {fmt.Printf("jsonStr = %s\n", jsonStr)newMovie := Moive{}err = json.Unmarshal(jsonStr, &newMovie)if err != nil {fmt.Printf("json unmarshal error %v\n", err)} else {fmt.Printf("newMoive: %v\n", newMovie)}}}func main() {user := User{11, "mike"}fmt.Println(user)FindTag(&user)movie := Moive{"喜剧之王", 2000, 10, []string{"周星驰", "张柏芝"}}ReadJson(movie)
}

$go.sum:h1:hash|xxx/go.modh1:hash$