100天精通Golang（基础入门篇）——第19天：深入剖析Go语言中方法（Method）的妙用与实践

func (t Type) methodName(parameter list)(return list) {
  
}
func funcName(parameter list)(return list){
    
}

package main

import (  
    "fmt"
)

type Employee struct {  
    name     string
    salary   int
    currency string
}

/*
 displaySalary() method has Employee as the receiver type
*/
func (e Employee) displaySalary() {  
    fmt.Printf("Salary of %s is %s%d", e.name, e.currency, e.salary)
}

func main() {  
    emp1 := Employee {
        name:     "Sam Adolf",
        salary:   5000,
        currency: "$",
    }
    emp1.displaySalary() //Calling displaySalary() method of Employee type
}

package main

import (
	"fmt"
	"math"
)

type Rectangle struct {
	width, height float64
}
type Circle struct {
	radius float64
}


func (r Rectangle) area() float64 {
	return r.width * r.height
}
//该 method 属于 Circle 类型对象中的方法
func (c Circle) area() float64 {
	return c.radius * c.radius * math.Pi
}
func main() {
	r1 := Rectangle{12, 2}
	r2 := Rectangle{9, 4}
	c1 := Circle{10}
	c2 := Circle{25}
	fmt.Println("Area of r1 is: ", r1.area())
	fmt.Println("Area of r2 is: ", r2.area())
	fmt.Println("Area of c1 is: ", c1.area())
	fmt.Println("Area of c2 is: ", c2.area())
}

Area of r1 is:  24
Area of r2 is:  36
Area of c1 is:  314.1592653589793
Area of c2 is:  1963.4954084936207

package main

import (  
    "fmt"
)

type Employee struct {  
    name     string
    salary   int
    currency string
}

/*
 displaySalary() method converted to function with Employee as parameter
*/
func displaySalary(e Employee) {  
    fmt.Printf("Salary of %s is %s%d", e.name, e.currency, e.salary)
}

func main() {  
    emp1 := Employee{
        name:     "Sam Adolf",
        salary:   5000,
        currency: "$",
    }
    displaySalary(emp1)
}

package main

import "fmt"

/* 声明全局变量 */
var g int

func main() {

   /* 声明局部变量 */
   var a, b int

   /* 初始化参数 */
   a = 10
   b = 20
   g = a + b

   fmt.Printf("结果： a = %d, b = %d and g = %d\n", a, b, g)
}

结果： a = 10, b = 20 and g = 30

func (b *Box) SetColor(c Color) {
	b.color = c
}

package main

import (
	"fmt"
)

type Rectangle struct {
	width, height int
}

func (r *Rectangle) setVal() {
	r.height = 20
}

func main() {
	p := Rectangle{1, 2}
	s := p
	p.setVal()
	fmt.Println(p.height, s.height)
}

20 2

package main

import "fmt"

type Human struct {
	name  string
	age   int
	phone string
}
type Student struct {
	Human  //匿名字段
	school string
}
type Employee struct {
	Human   //匿名字段
	company string
}

func (h *Human) SayHi() {
	fmt.Printf("Hi, I am %s you can call me on %s\n", h.name, h.phone)
}
func main() {
	mark := Student{Human{"Mark", 25, "222-222-YYYY"}, "MIT"}
	sam := Employee{Human{"Sam", 45, "111-888-XXXX"}, "Golang Inc"}
	mark.SayHi()
	sam.SayHi()
}

Hi, I am Mark you can call me on 222-222-YYYY
Hi, I am Sam you can call me on 111-888-XXXX

package main

import "fmt"

type Human struct {
	name  string
	age   int
	phone string
}
type Student struct {
	Human  //匿名字段
	school string
}
type Employee struct {
	Human   //匿名字段
	company string
}

//Human定义method
func (h *Human) SayHi() {
	fmt.Printf("Hi, I am %s you can call me on %s\n", h.name, h.phone)
}

//Employee的method重写Human的method
func (e *Employee) SayHi() {
	fmt.Printf("Hi, I am %s, I work at %s. Call me on %s\n", e.name,
		e.company, e.phone) //Yes you can split into 2 lines here.
}
func main() {
	mark := Student{Human{"Mark", 25, "222-222-YYYY"}, "MIT"}
	sam := Employee{Human{"Sam", 45, "111-888-XXXX"}, "Golang Inc"}
	mark.SayHi()
	sam.SayHi()
}

Hi, I am Mark you can call me on 222-222-YYYY
Hi, I am Sam, I work at Golang Inc. Call me on 111-888-XXXX

type Sayer interface {
    Say() string
}

type Dog struct {
}

func (d Dog) Say() string {
    return "Woof!"
}

type Cat struct {
}

func (c Cat) Say() string {
    return "Meow!"
}

func AnimalTalk(s Sayer) {
    fmt.Println(s.Say())
}

func main() {
    var d Sayer = Dog{}
    var c Sayer = Cat{}

    AnimalTalk(d)
    AnimalTalk(c)
}

type Geometry interface {
    Area() float64
    Perimeter() float64
}

type Square struct {
    side float64
}

func (s Square) Area() float64 {
    return s.side * s.side
}

func (s Square) Perimeter() float64 {
    return 4 * s.side
}

type Greeter struct {
    Name string
}

func (g Greeter) Greet() {
    fmt.Println("Hello", g.Name)
}

func main() {
    greet := Greeter{Name: "John"}.Greet
    greet()
}

type Adder struct {
    Base int
}

func (a Adder) Add(x int) int {
    return a.Base + x
}

func main() {
    add := Adder{Base: 2}.Add
    fmt.Println(add(3)) // Output: 5
}

package geometry

type Rectangle struct {
    Length, Width float64
}

func (r Rectangle) Area() float64 {
    return r.Length * r.Width
}

func (r Rectangle) perimeter() float64 {
    return 2 * (r.Length + r.Width)
}