4.Go- structure, the structure and methods pointer

4.1. Structure

Structure: one or more variables in combination with the formation of a new type, this is the type of structure, the structure is a value type

Definition of the structure and assignment

//Learn_Go/main.go
package main

import "fmt"

type People struct {
	Name string
	Age int
}

func main()  {
	var peo People
	fmt.Println(peo)           //{ 0}
	fmt.Printf("%p",&peo)     //0x110040f0

	// assignment
	//The first
	peo = People{"derek",20}
	fmt.Println(peo)      //{derek 20}
	// The second
	peo2 := People{Age:12,Name:"jack"}
	fmt.Println(peo2)     //{jack 12}

	// third
	peo.Name = "alice"
	peo.Age = 25
	fmt.Println(peo)     //{alice 25}
}

4.2. Structure pointer

Since the structure is a value type, when the transfer method of transfer desired address structure can be used to complete a structure pointer

May be combined with new () function creates a structure pointer

//Learn_Go/main.go
package main

import "fmt"

type People struct {
	Name string
	Age int
}

func main()  {
	peo := new(People)
	fmt.Println(peo)              //&{ 0}
	fmt.Println(peo == nil)       //false

	peo.Name = "derek"
	peo.Age = 22
	fmt.Println(peo)              //&{derek 22}

	peo2: = peo
	fmt.Println(peo2)            //&{derek 22}

	peo2.Name = "Jack"
	fmt.Println(peo, peo2)       //&{Jack 22} &{Jack 22}
}

4.3. Methods

Methods and functions more like syntax, except that the function package belongs, by calling the function package, the method belongs to the structure, the structure variable by calling

The default is a function, under the package, so it is necessary to label, which tells the compiler that this method belongs to the structure　

(1) creation method

//Learn_Go/main.go
package main

import "fmt"

type People struct {
	Name string
	Weight int
}

func (p People) run() {
	fmt.Println (p.Name, "is running, the current weight is:", p.Weight)
}

func main()  {
	peo := People{"derek",120}
	peo.run () // derek is running, the current body weight: 120
}

(2) modify the value of pointer

//Learn_Go/main.go
package main

import "fmt"

type People struct {
	Name string
	Weight int
}

func (p *People) run() {
	fmt.Println (p.Name, "is running, the current weight is:", p.Weight)
	// run once run method, body weight minus 1
	p.Weight -= 1
}

func main()  {
	peo := People{"derek",120}
	peo.run () // derek is running, the current body weight: 120
	fmt.Println ( "step after the finish of body weight:", peo.Weight) // step after the finish of body weight: 119
}

Source Address: https://www.cnblogs.com/derek1184405959/