与go邂逅(二)——基本程序结构

const (
	NUM1 = 1 + iota
	NUM2
	NUM3
	NUM4
)

//输出结果：1，2，4，8
func TestPrint(t *testing.T) {
	t.Log(NUM1, NUM2, NUM3, NUM4)
}

//数值交换
func TestExchange(t *testing.T) {
//也可以这样定义变量：var aa int = 1
	a := 1
	b := 2
	t.Log(a, b)
    //交换数值
	b, a = a, b
	t.Log(a, b)
}

//给类型命名
type typeInt int64

func TestInt(t *testing.T) {
	var a int64 = 2
	var b int32 = 3
	//类型不可转
	//a = b
	var c = typeInt(3)

	t.Log(a, b, c)
}

//斐波拉切
func TestFibList(t *testing.T) {
	var a int = 1
	var b int = 1
	t.Log(a)
	for i := 0; i < 5; i++ {
		t.Log(b)
		tmp := a + b
		a = b
		b = tmp
	}
}

//斐波拉切 递归
func TestFibRecursion(t *testing.T) {
	t.Log(FibRecursion(5))
}

func FibRecursion(i int) (result int) {
	if i == 1 || i == 2 {
		return 1
	}
	return FibRecursion(i-1) + FibRecursion(i-2)
}

//数组比较
func TestCompareArray(t *testing.T) {
	a := [...]int{1, 2, 3, 4}
	b := [...]int{1, 2, 2, 4}
	c := [...]int{1, 2, 3, 4}
	t.Log(a == b) //false
	t.Log(a == c) //true
}

func TestPoint(t *testing.T) {
	var a int64 = 1
	var aPtr = &a
	t.Log(a, aPtr)// 1 0xc420018230
	//打印类: int64 *int64
	t.Logf("%T %T", a, aPtr)
}

func TestString(t *testing.T) {
	//默认值是"" 不是java的那种null
	var str string
	t.Log("+" + str + "+")//输出++
}

//for循环  go 当中原来没有while
func TestFor(t *testing.T) {
	n := 5
	for n > 0 {
		t.Log(n)
		n--
	}
}

//for循环实现冒泡排序
func TestForSort(t *testing.T) {
	a := [...]int{3, 5, 2, 6, 4, 8, 2, 9,1,23,2,34,4,55,11}
	for i := 0; i < len(a)-1; i++ {
		for j := 0; j < len(a)-i-1; j++ {
			if a[j] > a[j+1] {
				tmp := a[j]
				a[j] = a[j+1]
				a[j+1] = tmp
			}
		}
	}

	t.Log(a)//[1 2 2 2 3 4 4 5 6 8 9 11 23 34 55]

}

//比较
func TestCondition(t *testing.T){
    //可以条件结果赋值给变量
	if a:=3>2;a{
		t.Log("3>2")
	}

	// GOOS is the running program's operating system target:
	// one of darwin, freebsd, linux, and so on.
	switch runtime.GOOS{
	//自带break
	case "darwin":
		t.Log("darwin")
	case "freebsd":
		t.Log("freebsd")
	case "linux":
		t.Log("linux")
	default:
		t.Log("default")
	}

	switch  {
	case 4>2:
		t.Log("4>2")
	case 4<2:
		t.Log("4<2")

	}
}