Go语言学习笔记(九)之数组

14.数组

数组定义以及初始化

数组是同一类型的元素集合(这和python不一样)。下面是定义一个数组,整数数组的元素默认初始化为0，字符串数组中的元素默认初始化为"",浮点型为0.0

  1: var a [3]int

  2: a[0]=10

  3: a[1]=20

  4: a[2]=30

  5: //另几种数组初始化

  6: var a [3]int = [3]int{10, 20, 30}

  7: a := [3]int{10,20,30}

  8: a := [...]int{10,20,30} //固定三个点

  9: a := [3]int{10}

 10: a := [3]int{2:10} // 2是10的下标

len(a)返回数组的长度

带索引的数组遍历

  1: var index, val int

  2: for index, val := range a {

  3: }

另一种遍历

  1: var a [5]int = [5]int {1, 3, 5, 8, 7}

  2: func main() {

  3: 	sum := 0

  4: 	for _, val := range a {

  5: 		sum += val

  6: 	}

  7: 	fmt.Println(sum)

  8: }

二维数组

  1: for i, val := range a{

  2: 	for j,val_2 := range val {

  3: 		//

  4: 	}

  5: }

数组拷贝和传参

  1: var a [3]int

  2: a[0] = 10

  3: a[1] = 20

  4: a[2] = 30

  1: func main(){

  2: 	b:=a

  3: 	b[0]= 1000

  4: 	fmt.Println(a, b)

  5: }

  6: >>> [1000 20 30] [1000 20 30]

  7: // 可以看出来这里是类似python里的深拷贝

另外一种

  1: func main() {

  2: 	var a []int = []int{10, 20, 30}

  3: 	modify(a)

  4: 	fmt.Println(a, b)

  5: }

  6: func modify(b []int) {

  7: 	b[0] = 1000

  8: 	return

  9: }

结果

  1: >>> [1000 20 30]

练习:
1.求数组所有元素之和

  1: var a [3]int = [3]int{10, 20, 30}

  2: func main() {

  3: 	sum := 0

  4: 	for i:=0; i<len(a);i++ {

  5: 		sum += a[i]

  6: 	}

  7: 	fmt.Println(sum)

  8: }

2.找出数组中和为给定值的两个元素的下标，比如数组:[1,3,5,8,7],找出两个元素之和等于8的下标分别是（0, 4）和(1, 2)

常规写法：

  1: var a [5]int = [5]int {1, 3, 5, 8, 7}

  2: func main()	{

  3: 	for i:=0; i<len(a); i++	{

  4: 		for j:=i+1; j<len(a)-i; j++{

  5: 			if a[i]+a[j] == 8 {

  6: 				fmt.Println(i, j)

  7: 			}

  8: 		}

  9: 	}

 10: }