go 入门教程变量

变量定义要求 ：Go 语言变量名由字母、数字、下划线组成，其中首个字符不能为数字

在描述变量定义以前，先描述下go 语言的结构

package main

import "fmt"
import "math"

func main()  {

 // 定义单一变量
     var age =18
    fmt.Println("my age is ",age)   
}

输出：my age is  18

// 定义多个变量

var width,height int = 100,50
    fmt.Println("width is ",width,"height is",height)

    输出： width is  100 height is 50

var (
        name = "zhangsan"
        age = 18
        job = "go"
        salary int
    )
    fmt.Println(" his name is",name, "age is",age, "job is",job, "salary is",salary)

    输出：  his name is zhangsan age is 18 job is IT salary is 0

go 的简短声明

简短声明的要求， := 左边的变量都有初始值 ,不然报错 例如 assignment mismatch: 3 variable but 2 values

name,age,job := "zhangsan",18,"IT"
    fmt.Println(name,age,job)

输出 ：zhangsan 18 IT

简短声明的语法要求 := 操做符的左边至少有一个变量是还没有声明的

x,y :=20,30
    fmt.Println("x is",x,"y is ",y)
    y,z := 40,50 
    fmt.Println("y is",y,"z is ",z)

正常输出： 

x is 20 y is  30
y is 40 z is  50

x,y :=20,30
x,y := 40,58
fmt.Println("x is",x ,"y is",y)

报错  no new variables on left side of :=，左边并无还没有声明的变量