Go learning record II (window)

go Study 20220523

---

go Environmental installation (window)

---

• choice windows Environment version , Download address is the same as Linux
  
• Click on the install , Specify the installation directory
  
• Configure environment variables
  win10 installed , Automatically generated environment variables , without , You need to add it manually
  
• Verification environment
  cmd–>go veriosn
  

Development tool installation

---

• download VScode development tool
  Download address
• install go plug-in unit
  
• Set up go Parameters
  Open Settings （ctrl+,）–> Search for golang–> Click on json edit
  

    "go.goroot": "D:\\Go\\bin",
    "go.gopath":"F:\\worker_go"

• Install related dependent components

go env -w GOPROXY=https://goproxy.cn
go install -v golang.org/x/tools/[email protected]

• Write code tests

package main

import "fmt"

func main() {
    
    fmt.Println("Hello, World!")
}

Conditional loop statement

---

• if sentence

package main

import "fmt"

func main() {
    
   /*  Defining local variables  */
   var a int = 66

   /*  Judge the condition  */
   if a > 90 {
    
       /* if  The conditional statement is  true  perform  */
       if a == 100 {
    
          /* if  The conditional statement is  true  perform  */
          fmt.Println(" perfect " );
       } else {
    
		  fmt.Println(" good " );
	   }
   } else if (a>80 && a<=90) {
    
       fmt.Println(" Great " );
   } else {
    
	   fmt.Println(" Other " );
   }
}

Change the value of the variable , To test

• switch
  fallthrough Will proceed to the next case, And will not judge whether the expression is true
  
• for
  if Add parentheses to execute , and java In the same way ,for no way , Adding parentheses will cause errors
  

Language structure

---

and Java It's very similar

package main

import "fmt"

type Car struct {
    
   brand string
   speed float64
   color string
}

func main() {
    
   /*  No, it is. Java Constructor to create objects */
   fmt.Println(Car{
    " Mercedes ",100.88," black "})

   fmt.Println(Car{
    brand:" Mercedes ",speed:100.88})

   /* Java Create objects for , attribute set value */
   var Benchi Car        /*  Statement  Benchi  by  Car  type  */
   Benchi.brand=" Big rush "
   Benchi.speed=111.11
   Benchi.color="red"
   fmt.Println(Benchi.brand)
   fmt.Println(Benchi.speed)
   fmt.Println(Benchi.color)
}

map

---

• map[key type]value type

package main

import "fmt"

func main() {
    
        /*  establish map */
        var testMap  map[string]string
		/*  initialization map */
		testMap = make(map[string]string)

		testMap["Name"]="Tom"
		testMap["face"]="big"
		for m := range testMap {
    
			fmt.Println(m, " The value is ", testMap [m])
		}
		for k,v := range testMap {
    
			fmt.Println(k, "=", v)
		}
		
}

• Multiple types value, Type designation

package main

import "fmt"

func main() {
    
        /*  establish map */
        var testMap  map[string]interface{
    }
		/*  initialization map */
		testMap = make(map[string]interface{
    })

		testMap["Name"]="Tom"
		testMap["age"]=99
		testMap["high"]=177.8
		for k,v := range testMap {
    
			fmt.Println(k, "=", v)
		}
		
}

Array slice

---

package main

import "fmt"

func main() {
    
	/* Array , Fixed length */
	shuzu := [3]int{
    1,2,3} 
	fmt.Println(" Array ===========================")
	for j := 0; j < 3; j++ {
    
		fmt.Println(shuzu[j])
	}
    /* section , The dynamic array , You can add elements dynamically */
	var shuzu1 = make([]int,3)// Specify the initial length of the slice （ The length of the array ）
	shuzu1 = []int{
    1,2,3} 
	fmt.Println(" section ===========================")
	shuzu1 = append(shuzu1,4)// Additional elements 
	shuzu1 = append(shuzu1,5,6,7)
	for j := 0; j < len(shuzu1); j++ {
    
		fmt.Println(shuzu1[j])
	}
}