Go language pointers

Pointers in Go language are easy to learn. Using pointers in Go language can make it easier to perform some tasks.

Next let’s learn Go language pointers step by step.

We all know that a variable is a convenient placeholder used to refer to a computer memory address.

The address character of Go language is &. When used before a variable, the memory address of the corresponding variable will be returned.

The following example demonstrates the address of a variable in memory:

package main

import "fmt"

func main() {
   var a int = 10   

   fmt.Printf("变量的地址: %x\n", &a  )
}

The output result of executing the above code is:

变量的地址: 20818a220

Now we have understood what a memory address is and how to access it it. Next we will introduce pointers in detail.

What is a pointer

A pointer variable can point to the memory address of any value. It points to the memory address of that value.

Similar to variables and constants, you need to declare a pointer before using it. The pointer declaration format is as follows:

var var_name *var-type

var-type is the pointer type, var_name is the pointer variable name, and the * sign is used to specify that the variable is used as a pointer. The following is a valid pointer declaration:

var ip *int        /* 指向整型*/
var fp *float32    /* 指向浮点型 */

In this case this is a pointer to an int and a float32.

How to use pointers

Pointer usage process:

• Define pointer variables.

• Assign a value to the pointer variable.

• Access the value pointing to the address in the pointer variable.

Add * (prefix) in front of the pointer type to get the content pointed to by the pointer.

package main

import "fmt"

func main() {
   var a int= 20   /* 声明实际变量 */
   var ip *int        /* 声明指针变量 */

   ip = &a  /* 指针变量的存储地址 */

   fmt.Printf("a 变量的地址是: %x\n", &a  )

   /* 指针变量的存储地址 */
   fmt.Printf("ip 变量的存储地址: %x\n", ip )

   /* 使用指针访问值 */
   fmt.Printf("*ip 变量的值: %d\n", *ip )
}

The execution output of the above example is:

a 变量的地址是: 20818a220
ip 变量的存储地址: 20818a220
*ip 变量的值: 20

Go null pointer

When a pointer is defined and no variable is assigned to it, its value is nil.

nil pointer is also called null pointer.

nil is conceptually the same as null, None, nil, and NULL in other languages, and they all refer to zero or empty values.

A pointer variable is usually abbreviated as ptr.

View the following examples:

package main

import "fmt"

func main() {
   var  ptr *int

   fmt.Printf("ptr 的值为 : %x\n", ptr  )
}

The output result of the above examples is:

ptr 的值为 : 0

Null pointer judgment:

if(ptr != nil)     /* ptr 不是空指针 */
if(ptr == nil)    /* ptr 是空指针 */

Go pointer more content

Next we will introduce you to more pointer applications in Go language: