Technology Sharing

한어Русский языкEnglishFrançaisIndonesianSanskrit日本語DeutschPortuguêsΕλληνικάespañolItalianoSuomalainenLatina

variable

Common variable declaration methods

1. Multiple ways to declare a single variable

1. Declare a variable and initialize a value

//声明变量 默认值是0，
	var a int
	//初始化一个值
	a = 1
	fmt.Println(a)

2. Omit during initializationtype of data, automatically matches the data type of the current variable through the value

	var b = 2
	fmt.Println("初始化值:", b)

3. Omit the var keyword and match automatically (cannot be used for global variables, only in function bodies)

	c := 3
	fmt.Println("初始化值:", c)

As follows, := cannotDeclaring global variables

2. How to declare multiple variables

//声明多个变量
	var h, i int = 10, 11
	fmt.Printf("h=%d,i=%dn", h, i)
	//多行的变量声明
	var (
		vv int  = 100
		jj bool = true
	)
	fmt.Println("vv=", vv, "jj=", jj)

The overall code demonstration is as follows:

package main
 
import "fmt"
 
var d int = 4
var e = 5
 
func main() {
	//变量声明方法
 
	声明变量 默认值是0，
	var a int
	//初始化一个值
	a = 1
	fmt.Println("a初始化值:", a)
	//
	//初始化的时候省去数据类型，通过自动匹配当前的变量的数据类型
	var b = 2
	fmt.Println("b初始化值:", b)
	//
	//
	c := 3
	fmt.Println("c初始化值:", c)
	//
	//
	打印全局变量
	fmt.Println("全局变量d=", d)
	fmt.Println("全局变量e=", e)
 
	fmt.Println("===================")
	//声明多个变量
	var h, i int = 10, 11
	fmt.Printf("h=%d,i=%dn", h, i)
	//多行的变量声明
	var (
		vv int  = 100
		jj bool = true
	)
	fmt.Println("vv=", vv, "jj=", jj)
 
}

constant

1. const

A constant is a simple identifier that does not change while the program is running.

The data types in constants can only be Boolean, numeric,Stringtype

The definition format of a constant is:

const identifier  [type] =value

The compiler can infer the type based on the value of the variable, and the type can be omitted

Display type definitions:

	//显示常量类型
	const a string = "五敷"
	fmt.Print("常量a:", a)

Implicit constant types

	//隐式常量类型
	const b = "有你"
	fmt.Println("常量b", b)

多个定义常量

	const (
		c = 0
		d = 1
		e = 2
	)
	fmt.Printf("c:%d,d:%d,e:%d", c, d, e)

2. iota and expressions

 iotacan do more than just increment. More precisely,iotaAlways used for increment, but it can be used in expressions, storing the resulting value in a constant.

	const (
		aa = iota + 1
		bb = iota + 100 //会沿用iota的值
	)
	fmt.Printf("aa=%d，bb=%d", aa, bb)
	//iota总是用于 increment，但是它可以用于表达式
	const (
		express1, express2 = iota + 1, iota + 2
		express3, express4
		express5, express6
	)
	fmt.Println("express1,express2,express3,express4=>", express1, express2, express3, express4, express5, express6)

Note: iota can only be used in const