一、第一个go语言程序

1.新的开始，从hello world启航

package main

import "fmt"

func main() {
	fmt.Println("hello world")
}

2.定义变量

package main

import "fmt"

//包内变量
var as = 3
var ss = "kk"
var bb = true

var (
	aa=3
)

func variableZeroValue() {
	var a int
	var s string
	fmt.Printf("%d %q\n", a, s)
}

func variableInitialValue() {
	var a, b = 3, 4
	var s = "abc"
	fmt.Println(a, b, s)
}

func variableTypeDeduction() {
	var a, b, c, s = 3, 4, true, "def"
	fmt.Println(a, b, c, s)
}

func variableShorter() {
	a, b, c, s := 3, 4, true, "def"
	b = 5
	fmt.Println(a, b, c, s)
}

func main() {
	fmt.Println("hello world")
	variableZeroValue()
	variableInitialValue()
	variableTypeDeduction()
	variableShorter()
	fmt.Println(aa,as,ss,bb)
}

3.小结
3.1使用var关键字：1.var a, b, C bool,2.var s1, s2 string = "hello", "world" , 3.可放在函数内, 或直接放在包内,4.使用var()集中定义变量
3.2让编译器自动决定类型vara,b,i,s1,s2 = true, false, 3, "hello", "world"
3.3使用:=定义变量，a,b,i, s1, s2 := true, false, 3, "hello", "world"