Slice overview
Simply put, a slice can be understood as a dynamic array, the length is not fixed, but it is not an array .
Creation of slices
- Use var
var name []Type
//例如
var s []int //[]中不需要指定特定长度
//输出
[]
- automatic derivation
name := []Type{
}
//例如
s := []int{
1,2,3}
//输出
[1,2,3]
- Use make function
name := make([]Type,len,cap) //len是长度，cap是容量，cap可省略，此时len==cap
//例如
s := make([]int,3,5) //len(s)=3,cap(s)=5
//输出
[0,0,0]
Slice initialization
- direct initialization
var s []int = []int{
1,2,3}
s1 := []int{
1,2,3,4}
- appendadd
s = append(s,4) //此时s = [1,2,3,4]
- for loop initialization
s2 := make([]int,3,5)
for i:=0;i<len(s2);i++{
s2[i] = i
}
//s2 = [0,1,2]
- Single item assignment and modification
s2[2] = 999
//s2 = [0,1,999]
Slice traversal
- for…len method
s:=[]int{
1,2,3}
for i:=0;i<len(s);i++{
//可以输出每项s[i]
}
2.for…range method
s:=[]int{
1,2,3}
for index,value := range s{
//index 是索引下标，value是索引对应的值
}
//若不需要处理索引或者值可以使用 _ 省略，例如
for _,value := range s{
//index 是索引下标，value是索引对应的值
}
Slice interception
s[n] //切片s中索引位置为n的项
s[:] //从切片s的索引位置0到len(s)-1处所获得的切片
s[low:] //从切片s的索引位置low到len(s)-1处所获得的切片
s[:high] //从切片s的索引位置0到high处（不包含high）所获得的切片m,len = high
s[low:high] //从切片s的索引位置low到high处（不包含high）所获得的切片,len = high - low
s[low:high:max] //从切片s的索引位置low到high处（不包含high）所获得的切片,len = high - low ,cap = max-low,max 切片中最多能够容纳多少元素
//s[low:high:max] 演示
s := []int{
1,2,3,4,5,6}
s1 := s[0:3:5]
//输出
//s1 = [1,2,3] 不包含下标为3的值 0 1 2
//len(s1) = 3
//cap(s1) = 5-0 = 5
The general calculation formula for capacity cap is cap = max - low
Modifying the value of the intercepted slice will affect the content of the original slice
s := []int{
1,2,3,4,5,6}
s1 := s[0:3:5] //s1并不是开辟了新的空间而是指向了原切片s
s1[0] = 999
//输出
s1 = [999,2,3]
s = [999,2,3,4,5,6]
Basic usage of append function
The append function adds elements to the end of the slice
s := make([]int,5,8)
//s = [0,0,0,0,0]
s = append(s,1)
//s = [0,0,0,0,0,1]
s = append(s,2)
s = append(s,3)
//s = [0,0,0,0,0,1,2,3] len(s) = 8 cap = 8 已到达切片定义时的容量
s = append(s,4)
//s = [0,0,0,0,0,1,2,3,4] len(s) = 9 cap = 16
//当追加的元素超过定义切片的容量时，会自动扩容，一般扩容方式为上一下cap的两倍，即cap*2
//如果超过1024字节，每次扩容上一次的大约1/4.即约cap*（1+1/4）
Use of copy function
//copy(切片1，切片2)
s1 := []int{
1,2}
s2 := []int{
3,4,5,6,7}
copy(s1,s2)
//s1 = [3,4]
//copy(切片1，切片2)
s1 := []int{
1,2}
s2 := []int{
3,4,5,6,7}
copy(s2,s1)
//s2 = [1,2,5,6,7]
Slices as function parameters
func main(){
s := []int{
1,2,3,4,5}
init(s)
}
func init(num []int){
for _,v := range num {
fmt.printf("%d ",v)
}
}
//输出
1 2 3 4 5
Note: Modifying the value of the slice in the function will affect the original slice, but the array will not .
func main(){
s := []int{
1,2,3,4,5}
init(s)
fmt.println()
fmt.println(s)
}
func init(num []int){
for _,v := range num {
fmt.printf("%d ",v)
}
num[0] = 999
}
//输出
1 2 3 4 5
[999,2,3,4,5]
Slicing Case 1—Calculate the sum of a specific number of integer data
package main
import "fmt"
func main() {
var count int
fmt.Println("请输入计算整数和的数量：")
fmt.Scan(&count)
num := make([]int,count)
fmt.Println("请输入",count,"个整数：")
for i:=0;i<len(num);i++{
fmt.Scan(&num[i])
}
result := sum(num)
fmt.Println("整数和为：",result)
}
func sum(num []int) int {
result := 0
for _,v := range num{
result = result+v
}
return result
}
Slicing case 2—Output the maximum value in an integer array of variable length
package main
import "fmt"
func main() {
var count int
fmt.Println("请输入计算最大值的整数数量：")
fmt.Scan(&count)
num := make([]int,count)
fmt.Println("请输入",count,"个整数：")
for i:=0;i<len(num);i++{
fmt.Scan(&num[i])
}
result := PrintMax(num)
fmt.Println("最大整数为：",result)
}
func PrintMax(num []int) int {
result := 0
for _,v := range num{
if v > result {
result = v
}
}
return result
}
