import "fmt"
import (
        "fmt"
        "math"
)

fmt.Println(math.Pi,math.Nextafter(2,3))

math.Nextafter(2,3)  为何返回一直是  2.0000000000000004

func add(x int, y int) int {
        return x + y
}

x省略类型，与后面的y一样
func add2(x ,y int) int {
        return x + y
}


多值返回
func swap(x, y string) (string, string) {
        return y, x
}
 
返回参数命名
func add4(x,y int) (sum int) {
        sum = x + y
        return
}

变量声明和类型推断

var a,b int
var a1,b1 int = 1,2
var a2,b2,c3=1,"hello",true
var a3,b3  =5,6

函数外不能使用隐式变量声明，譬如 a : = 3 


常量声明
const Pi = 3.14


const (
        Big = 1<<100
        Small = Big>>99  // 2
)
// int 2 
fmt.Printf("%T %v \n",Small,Small)

// overflows int
// fmt.Printf("%T %v \n",Big,Big)
这个 Big 到底是什么类型？



完整代码

package main

import(
"fmt"
"math"
"time"
)

func add(x int, y int) int {
        return x + y
}
func add2(x ,y int) int {
        return x + y
}
func add3(x int, y float64) int {
        return x + int(y)
}
func add4(x,y int) (sum int) {
        sum = x + y
        return
}
func swap(x, y string) (string, string) {
        return y, x
}
 
var a,b int
var a1,b1 int = 1,2
var a2,b2,c2=1,"hello",true
var a3,b3  =5,6
const Pi = 3.14

const (
        Big = 1<<100
        Small = Big>>99  // 2
)

func main() {
	fmt.Println(time.Now())
	time.Sleep(time.Duration(1)*time.Second)
	fmt.Println(time.Now())
        fmt.Println(math.Pi,math.Nextafter(2,3))
	fmt.Println(add(1,2))
        fmt.Println(add2(2,3))
	fmt.Println(add3(1,1.1))
	fmt.Println(add4(7,1))

	fmt.Println(swap("hello","world"))
	
	fmt.Println(a,b)
	fmt.Println(a1,b1)
	fmt.Println(a2,b2)
	fmt.Println(a3,b3)
	fmt.Println(a2,b2,c2)
	fmt.Printf("%T %T %T \n",a2,b2,c2)

	fmt.Printf("%T %v \n",Pi,Pi)

	fmt.Printf("%T %v \n",Small,Small)

	// fmt.Printf("%T %v \n",Big,Big)


}