Video source ：B standing 《golang Introduction to project practice [2021 newest Go Language course , There is no nonsense , Dry only ！ Ongoing update ...]》

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Go The function parameters in the language are all value copies , When we want to modify a variable , We can create a pointer to the address of the variable . Passing data using pointers , Without copying data .

Type pointers cannot be offset and operated .

Go Pointer operation in language is very simple , Just remember two symbols ：&（ Address fetch ） and *（ According to the address ）

Pointer address and pointer type

Each variable has an address at run time , This address represents the location of the variable in memory .Go Used in language & The character is placed in front of the variable to address the variable .Go Value types in languages （int、float、bool、string、array、struct） All have corresponding pointer types , Such as ：*int、*int64、*string etc. .

Pointer Syntax

A pointer variable points to the memory address of a value .（ That is, after we declare a pointer , It can be assigned as a variable , Put the memory address of a value into the pointer .）

Similar to variables and constants , You need to declare pointers before using them . The format of the pointer declaration is as follows ：

var var_name *var-type

var-type： Is pointer type

var_name： Is the pointer variable name

*： Used to specify that the variable is used as a pointer .

Pointer declaration example

var ip *int     /*  Directed integer  */
var fp *float32 /*  Point to floating point  */

Pointer usage example

package main

import "fmt"

func main() {
    var a int = 20 /*  Declare the actual variable  */
    var ip *int    /*  Declare pointer variables  */
    ip = &a        /*  Storage address of pointer variable  */
    fmt.Printf("a The address of the variable is : %x\n", &a)
    /*  Storage address of pointer variable  */
    fmt.Printf("ip Pointer address of variable storage : %x\n", ip)
    /*  Use a pointer to access  */
    fmt.Printf("*ip The value of the variable : %d\n", *ip)
}

Running results

[Running] go run "d:\SynologyDrive\ software development \go\golang Introduction to project practice \goproject\360duote.com\pro01\test.go"
a The address of the variable is : c000014098
ip Pointer address of variable storage : c000014098
*ip The value of the variable : 20