Go语言切片学习

切片的三种定义

package main

import "fmt"

func main() {

//切片定义1
var slice []int //空切片

fmt.Println(slice)   //打印结果  []


//追加元素 
slice = append(slice, 1,2,3)

fmt.Println(len(slice))//长度  3
fmt.Println(cap(slice))//容量  4

//切片定义2
var s1 []int=[]int{1,2,3}
fmt.Println(s1)    //打印结果 [1 2 3]
s2:=[]int{1,2,3}
fmt.Println(s2)   //打印结果 [1 2 3]

//切片定义3
//make 函数 （切片，长度，容量）

//s :=make([]int,5,10)
s:=make([]int,5)  //容量可以省略
fmt.Println(s)  // 打印结果 [0 0 0 0 0]
s=append(s, 1,2,3,4,5)

fmt.Println(s)  // 打印结果 [0 0 0 0 0 1 2 3 4 5]
s=append(s, 6,7,8)

fmt.Println(s) //打印结果 [0 0 0 0 0 1 2 3 4 5 6 7 8]

//在追加数据时长度超过容量，容量会自动扩容，一般是上一次容量x2 如果超过1024字节 每次扩容上一次1/4 容量扩容每次都是偶数
s11 :=make([]int,0,1)
oldcap:=cap(s11)
for i:=0;i<200000;i++{
    s11=append(s11,i)
    newcap:=cap(s11)
    if oldcap<cap(s11){
        fmt.Printf("cap:%d  == %d\n",oldcap,newcap)
        oldcap=newcap
    }
}


//输出结果：

//cap:1  == 2
//cap:2  == 4
//cap:4  == 8
//cap:8  == 16
//cap:16  == 32
//cap:32  == 64
//cap:64  == 128
//cap:128  == 256
//cap:256  == 512
//cap:512  == 1024
//cap:1024  == 1280
//cap:1280  == 1696
//cap:1696  == 2304
//cap:2304  == 3072
//cap:3072  == 4096
//cap:4096  == 5120
//cap:5120  == 7168
//cap:7168  == 9216
//cap:9216  == 12288
//cap:12288  == 15360
//cap:15360  == 19456
//cap:19456  == 24576
//cap:24576  == 30720
//cap:30720  == 38912
//cap:38912  == 49152
//cap:49152  == 61440
//cap:61440  == 76800
//cap:76800  == 96256
 //cap:96256  == 120832
 //cap:120832  == 151552
 //cap:151552  == 189440
 //cap:189440  == 237568


//切片截取

section :=[]int{10,20,30,40,50}
//   section[起始位置 low ：结束位置(不包含) heigh：max]
// len = low-heigh
// cap = max-low
//newsection :=section[0:4:5]   
//newsection :=section[0:4]
//newsection :=section[:4]
newsection :=section[2:]

newsection[2]=999//截取后的切片还是原始切片中的一块内容，所以修改后的切片影响原始切片
fmt.Println(section)
fmt.Println(newsection)

 }