go语言渐入佳境[13]-切片-创新互联

//切片的声明1  //nil
var slice1 []int  

//切片的声明2
var slice2 []int = make([]int,5)
var slice3 []int = make([]int,5,7)
numbers:= []int{1,2,3,4,5,6,7,8}

numbers:= []int{1,2,3,4,5,6,7,8}
//从下标1一直到下标4，但是不包括下标4
numbers1 :=numbers[1:4]
//从下标0一直到下标3，但是不包括下标3
numbers2 :=numbers[:3]
//从下标3一直到结束
numbers3 :=numbers[3:]

package main

import "fmt"

//1、切片可以修改大小

//2、切片的拷贝不是单纯值的拷贝，一个切片指向了一个数组


//切片的声明1
var slice1 []int

//切片的声明2
var slice2 []int = make([]int,5)
var slice3 []int = make([]int,5,7)

func main(){


slice4 := make([]int,5)
slice5 := make([]int,5,7)

slice6 := make([]int,0)


fmt.Printf("len=%d,cap=%d,slice=%v\n",len(slice4),cap(slice4),slice4)
fmt.Printf("len=%d,cap=%d,slice=%v",len(slice5),cap(slice5),slice5)


if slice4 ==nil{
fmt.Printf("len=%d,cap=%d,slice=%v\n",len(slice4),cap(slice4),slice4)

}
//	slice6 := make([]int,0)不为nil
if slice6 !=nil{
fmt.Printf("len=%d,cap=%d,slice=%v\n",len(slice6),cap(slice6),slice6)

}
//var slice1 []int为nil
if slice1 ==nil{
fmt.Printf("len=%d,cap=%d,slice=%v\n",len(slice1),cap(slice1),slice1)

}

sliceTest()
}

//截取
func sliceTest(){
numbers:= []int{1,2,3,4,5,6,7,8}
printSliceInfo(numbers)

numbers1 :=numbers[1:4]
printSliceInfo(numbers1)


numbers2 :=numbers[:3]
printSliceInfo(numbers2)

numbers3 :=numbers[3:]
printSliceInfo(numbers3)
}
//打印切片
func printSliceInfo(x []int){

fmt.Printf("len=%d,cap=%d,slice=%v\n",len(x),cap(x),x)
}

//	切片删除
//	删除第一个元素
numbers = numbers[1:]  

//	删除最后一个
numbers = numbers[:len(numbers)-1]

//删除中间一个元素
a := int(len(numbers) / 2)
numbers = append(numbers[:a], numbers[a+1:]...)

package main

import "fmt"

func main() {
//数组是值类型
a := [4]int{1, 2, 3, 4}

//切片是引用类型
b := []int{100, 200, 300}

c := a
d := b

c[1] = 200
d[0] = 1

fmt.Println("a=", a, "c=", c)
//c[1 200 3 4] a[1 2 3 4]
fmt.Println("b=", b, "d=", d)
//d[1 200 300]  b[1 200 300]
}

numbers := make([]int, 0, 20)


//append一个元素
numbers = append(numbers, 0)

//append多个元素
numbers = append(numbers, 1, 2, 3, 4, 5, 6, 7)


//append添加切片
s1 := []int{100, 200, 300, 400, 500, 600, 700}
numbers = append(numbers, s1...) //[0 1 2 3 4 5 6 7 100 200 300 400 500 600 700]

//创建目标切片
numbers1 := make([]int, len(numbers), cap(numbers)*2)

//	将numbers的元素拷贝到numbers1中
count := copy(numbers1, numbers)

package main

import "fmt"

func main() {
fmt.Println("1、--------------")
//var numbers []int
numbers := make([]int, 0, 20)


//append一个元素
numbers = append(numbers, 0)
printSlice("numbers:", numbers) //[0]

//append多个元素
numbers = append(numbers, 1, 2, 3, 4, 5, 6, 7)
printSlice("numbers:", numbers) //[0 1 2 3 4 5 6 7]

//append添加切片
s1 := []int{100, 200, 300, 400, 500, 600, 700}
numbers = append(numbers, s1...) //[0 1 2 3 4 5 6 7 100 200 300 400 500 600 700]
printSlice("numbers:", numbers)





fmt.Println("2、--------------")
//	切片删除
//	删除第一个元素
numbers = numbers[1:]
printSlice("numbers:", numbers) //[ 1 2 3 4 5 6 7 100 200 300 400 500 600 700]

//	删除最后一个
numbers = numbers[:len(numbers)-1]
printSlice("numbers:", numbers) //[ 1 2 3 4 5 6 7 100 200 300 400 500 600]

//删除中间一个元素
a := int(len(numbers) / 2)
fmt.Println("中间下标：", a)
numbers = append(numbers[:a], numbers[a+1:]...)
printSlice("numbers:", numbers) //[1 2 3 4 5 6 100 200 300 400 500 600]




fmt.Println("3、--------------")
//创建目标切片
numbers1 := make([]int, len(numbers), cap(numbers)*2)

//	将numbers的元素拷贝到numbers1中
count := copy(numbers1, numbers)
fmt.Println("拷贝的个数：", count)
printSlice("numbers1:", numbers1)

//拷贝的两个切片是否有关联
numbers[0] = 99
numbers1[len(numbers1)-1] = 100

printSlice("numbers", numbers)
printSlice("numbers1", numbers1)

}

func printSlice(name string, x []int) {
fmt.Print(name, "\t")
fmt.Printf("地址：%p \t len=%d \t cap=%d \t value=%v \n", x, len(x), cap(x), x)
}

package main

import "fmt"

func f(s []string, level int) {
       if level > 5 {
              return
       }
       s = append(s, fmt.Sprint(level))
       f(s, level+1)
       fmt.Println("level:", level, "slice:", s)
}

func main() {
       f(nil, 0)
}

level: 5 slice: [0 1 2 3 4 5]
level: 4 slice: [0 1 2 3 4]
level: 3 slice: [0 1 2 3]
level: 2 slice: [0 1 2]
level: 1 slice: [0 1]
level: 0 slice: [0]