Golang中的Slice与数组及区别详解

func main() {
 var arr1 = [...]int{1,2,3,4} //[...]默认为元素的数量即为数组的长度
 fmt.Println(len(arr1)) //4
 arr1[4] = 5 //panic 数组越界
 fmt.Println(arr1)
 var arr2 = [10]int{1,2,3,4}
 fmt.Println(arr2) //[1 2 3 4 0 0 0 0 0 0]
}

func main() {
 var arr = [10]int{4,5,7,11,8,9}
 fmt.Println(arr) //[4,5,7,11,8,9,0,0,0,0]
 //验证数组是值拷贝传递
 AddOne(arr)
 fmt.Println(arr) //[4,5,7,11,8,9,0,0,0,0]
}
func AddOne(arr [10]int){
 arr[9] = 999999
 fmt.Println(arr) //[4,5,7,11,8,9,0,0,0,999999]
}

type slice struct {
 array unsafe.Pointer
 len int
 cap int
}

func main() {
  var arr = [...]int{0,1,2,3,4,5,6}
  slice1 := arr[1:4:5] //{low:high:max} 最多再扩张一个元素
  //max超出 len(arr)
  //slice2 := arr[1:4:7] //panic
  fmt.Println(slice1) //[1,2,3]
  slice3 := slice1[1:3:4] //[2,3] 大于4会panic
  fmt.Println(slice3)
}

func main() {
  var slice = make([]int,3,5) //len=3,cap=5
  fmt.Println(slice)  //[0,0,0]
  slice2:=slice[:5]  //slice实现了对slice的扩容,切片长度变为5
  fmt.Println(slice2) //[0,0,0,0,0]
}

func main() {
  var slice = make([]int,3,5) //len=3,cap=5
  fmt.Println(slice)  //[0,0,0]
  slice2:=slice[:5]  //slice实现了对slice的扩容,切片长度变为5
  fmt.Println(slice2) //[0,0,0,0,0]
  slice[0] = 999  //这里slice和slice的index=0位置都是999 因为他们引用的底层数组的index=0位置都是999
  fmt.Println(slice)
  fmt.Println(slice2)
  AddOne(slice) //[8888,0,0]
  fmt.Println(slice) //[8888,0,0]
  fmt.Println(slice2) //[8888,0,0,0]
}
func AddOne(s []int){
 s[0] = 8888
 fmt.Println(s)
}

func main() {
  var arr = [...]int{1,2,3,4}
  fmt.Println(arr) //[1,2,3,4]
  slice := arr[:]
  fmt.Println(slice) //[1,2,3,4]
  slice = append(slice,[]int{5,6,7}...) //此时slice的引用地址已经发生改变了,它引用的底层数组再也不是arr了,而是一个新的数组newarr[1,2,3,4,5,6,7]
  fmt.Println(slice) //[1,2,3,4,5,6,7]
  //验证slice引用的地址已经发生改变
  slice[0] = 666
  fmt.Println(arr) //[1,2,3,4]
  fmt.Println(slice) //[666,2,3,4,5,6,7]
}

func main() {
  var arr = [6]int{1,2,3,4}
  fmt.Println(arr) //[1,2,3,4,0,0]
  slice := arr[:4]
  fmt.Println(slice) //[1,2,3,4]
  slice = append(slice,5)
  fmt.Println(arr) //[1,2,3,4,5,0]
  fmt.Println(slice) //[1,2,3,4,5]
}