Table of Contents
Why variables are needed" >Why variables are needed
Variable definition" >Variable definition
Declaration of variables" >Declaration of variables
Batch declaration
" >Batch declaration
声明时赋值
" >声明时赋值
在Go中的一个强制要求
" >在Go中的一个强制要求
类型推导方式声明变量赋值
" >类型推导方式声明变量赋值
:=方式变量赋值" >:=方式变量赋值
全局变量
" >全局变量
匿名变量" >匿名变量
常量" >常量
Home Backend Development Golang An article to help you understand the basic variables of Go language

An article to help you understand the basic variables of Go language

Jul 20, 2023 pm 03:51 PM
variable go language

Why variables are needed

To put it simply, the program we write defaultsData are all stored in the memory stick. It is impossible for us to find this variable directly through the address because the address is too long and difficult to remember.

Usually we find the address corresponding to through the variable name ##The above value is , and then perform a series of operations.

An article to help you understand the basic variables of Go language

Variable types

Now, no matter what language it is, commonly used variables are divided into the following types.

  • Integer, 1, 6, 2, 8, 4...

  • Floating point number, 1.1, 5.7767, 23.99...

  • Boolean, True, False

  • String Type, "Zhang San", "李思"...

  • List

  • Map

It will probably be divided into the above types, but you don’t need to remember this, just understand it.


Variable definition

Declaration of variables

The format is as follows.

var 变量名 变量类型
例如:
var age int
var gender bool
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Batch declaration

The variables declared above are declared one by one. If you need to declare them all at once Some variables can be written like this.

var (
    age int
    gender bool
    name string
    id int
    height int
    ...
)
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声明时赋值

上述方式,只是声明了变量,但是并没有赋值,在后期需要时可以在赋值。

如果在声明时,就确定值是什么,可以直接赋值。

格式如下。

var 变量名 类型 = 值
例如:
var age int = 18
var name string = "张三"
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在Go中的一个强制要求

在Go中,变量必须使用,至少需要fmt.Println(变量)

An article to help you understand the basic variables of Go language

类型推导方式声明变量赋值

在上述声明变量并且赋值时,还需要指定变量类型。

在Go,Go具有类型推导方式声明时赋值变量。

var age = 18
var name = "张三"
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其实就是变量名后面不用写变量类型了。

:=方式变量赋值

在Go,还有一种更简单的方式声明变量赋值。

格式如下。

age := 18
name := "张三"
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学过Python的可能有点开心了,除了多个一个:号,其他基本和Pyton定义变量方式一样。

注意:

age := 18 //本质是执行的两句话
//同上
var age int
age = 18
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全局变量

简单说就是,在最外面的定义的变量就是全局变量。

在Go中,全局变量是有要求的。

package main

//全局变量:
// 方式一,声明全局变量,必须跟类型
//var age int

//方式二,声明变量且赋值,类型可以不用写
//var age  = 18
//var age  int = 18

//方式三,错误示例,全局变量要么只声明变量,要么声明就赋值
//var age int
//age =18

//方式四,错误示例,:=方式声明赋值
// 方式四其实就等于方式三的写法,所以不能用在全局变量中
//age := 18

func main() {

}
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PS:全局变量要么只声明,要么声明时就赋值,不能写两行赋值,所以:=方式不能应用在全局变量中

匿名变量

匿名变量多用于函数返回值场景中,比如函数返回了俩值,俩值要第一个值,就可以使用匿名变量。

因为Go中,变量必须使用,如果某个变量需要忽略,使用_即可。

值得注意的是,匿名变量不会占用内存。

package main
func get_info() (string, int) {
    return "张三", 18
}
func main() {
    //标准写法
    //name, age := get_info()
    //fmt.Println(name, age)

    //匿名变量方式
    //name, _ := get_info()
    //fmt.Println(name)

    //_,age := get_info()
    //fmt.Println(age)
}
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常量

其实常量和变量基本一样,但是常量是不能修改的。

通常常量以大写定义。

package main

import "fmt"

func main() {
    //单个声明
  const PI1 int = 3
  const PI2 = 3.14
  //同时声明多个
  const (
    PI3 = 3.14
    PI4 = 3.14
  )
  //同上声明多个变量时,如果省略了值表示和上一行相同
  const (
    girl1 = 18
    girl2 // 18,和上一行相同
    girl3 // 18,和上一行相同
    girl4 = 17
    girl5 // 17,和上一行相同

  )
  fmt.Println(girl3, girl5)
}
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注:常量声明时就必须赋值

错误示例。

package main

func main() {
  const age int
  age = 18
    //error
}
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