go--学习笔记--第二章

hello world

package main    //开头标配

import "fmt"    //实现格式化的I/O

func main() {
	fmt.Printf("hello")
	
}

变量

var a int
var b int32
/*数字类型*/

var b bool
b = false
/*布尔类型*/

const (
           a = iota
          )
/*常量*/ iota生成枚举值

for循环

for i := 0' i<10; i++ ()    //正常循环
for condition()    //类似while
for ()    //死循环

打印数字

package main

import "fmt"

func main()  {
	for i:=0; i<10; i++ {
		fmt.Printf("%d\n", i)
	}
}

/*改良1*/
package main

import "fmt"

func main()  {
	i := 0
I:
	fmt.Printf("%d\n", i)
	i++
	if i < 10{
		goto I
	}
}

/*改良2*/
package main

import "fmt"

func main()  {
	var arr [10] int
	for i := 0; i<10; i++ {
		arr[i] = i
	}
	fmt.Printf("%v", arr)
}

/*改良3*/
package main

import "fmt"

func main()  {
	a := [...]int{0,1,2,3,4,5,6,7,8,9}
	fmt.Printf("%v",a)
}

余数提示

package main

import "fmt"

func main()  {
	const (
		FIZZ = 3
		BUZZ = 5
	)
	var p bool
	for i := 1; i < 100; i++ {
		p = false
		if i%FIZZ == 0{
			fmt.Printf("FIZZ")
			p = true
		}
		if i%BUZZ == 0{
			fmt.Printf("BUZZ")
			p = true
		}
		if !p {
			fmt.Printf("%v", i)
		}
		fmt.Println()
	}
}

打印a

package main

import "fmt"

func main()  {
	str := "A"
	for i := 0; i < 10; i++ {
		fmt.Printf("%s\n", str)
		str = str + "A"
	}
}

####反向打印

package main

import "fmt"

func main()  {
	s := "foobar"
	a := []rune(s)
	for i, j := 0, len(a)-1; i<j; i, j = i+1, j-1 {
		a[i], a[j] = a[j], a[i]
	}
	fmt.Printf("%s\n", string(a))
}

平均数

package main

func main()  {
	sum := 0.0
	switch len(xs) {

	case 0:
		avg = 0
	default:
		for _, v := range xs {
			sum += v
		}
		avg = sum / float64(len(xs))
	}
}