Go - sliced

Outline

A slice is a dynamic array, flexible operation than the array length is not fixed, it may be added and deleted.

len()And cap()return results may be the same and different.

Statement sliced

//demo_7.go
package main

import (
    "fmt"
)

func main() {
    var sli_1 [] int      //nil 切片
    fmt.Printf("len=%d cap=%d slice=%v\n",len(sli_1),cap(sli_1),sli_1)

    var sli_2 = [] int {} //空切片
    fmt.Printf("len=%d cap=%d slice=%v\n",len(sli_1),cap(sli_2),sli_2)

    var sli_3 = [] int {1, 2, 3, 4, 5}
    fmt.Printf("len=%d cap=%d slice=%v\n",len(sli_3),cap(sli_3),sli_3)

    sli_4 := [] int {1, 2, 3, 4, 5}
    fmt.Printf("len=%d cap=%d slice=%v\n",len(sli_4),cap(sli_4),sli_4)

    var sli_5 [] int = make([] int, 5, 8)
    fmt.Printf("len=%d cap=%d slice=%v\n",len(sli_5),cap(sli_5),sli_5)

    sli_6 := make([] int, 5, 9)
    fmt.Printf("len=%d cap=%d slice=%v\n",len(sli_6),cap(sli_6),sli_6)
}

operation result:

Interception sliced

//demo_8.go
package main

import (
    "fmt"
)

func main() {
    sli := [] int {1, 2, 3, 4, 5, 6}
    fmt.Printf("len=%d cap=%d slice=%v\n",len(sli),cap(sli),sli)

    fmt.Println("sli[1] ==", sli[1])
    fmt.Println("sli[:] ==", sli[:])
    fmt.Println("sli[1:] ==", sli[1:])
    fmt.Println("sli[:4] ==", sli[:4])
    
    fmt.Println("sli[0:3] ==", sli[0:3])
    fmt.Printf("len=%d cap=%d slice=%v\n",len(sli[0:3]),cap(sli[0:3]),sli[0:3])

    fmt.Println("sli[0:3:4] ==", sli[0:3:4])
    fmt.Printf("len=%d cap=%d slice=%v\n",len(sli[0:3:4]),cap(sli[0:3:4]),sli[0:3:4])
}

operation result:

Additional sections

//demo_9.go
package main

import (
    "fmt"
)

func main() {
    sli := [] int {4, 5, 6}
    fmt.Printf("len=%d cap=%d slice=%v\n",len(sli),cap(sli),sli)

    sli = append(sli, 7)
    fmt.Printf("len=%d cap=%d slice=%v\n",len(sli),cap(sli),sli)

    sli = append(sli, 8)
    fmt.Printf("len=%d cap=%d slice=%v\n",len(sli),cap(sli),sli)

    sli = append(sli, 9)
    fmt.Printf("len=%d cap=%d slice=%v\n",len(sli),cap(sli),sli)

    sli = append(sli, 10)
    fmt.Printf("len=%d cap=%d slice=%v\n",len(sli),cap(sli),sli)
}

operation result:

When append, insufficient capacity expansion when needed, cap will be doubled.

Delete sections

//demo_10.go
package main

import (
    "fmt"
)

func main() {
    sli := [] int {1, 2, 3, 4, 5, 6, 7, 8}
    fmt.Printf("len=%d cap=%d slice=%v\n",len(sli),cap(sli),sli)

    //删除尾部 2 个元素
    fmt.Printf("len=%d cap=%d slice=%v\n",len(sli[:len(sli)-2]),cap(sli[:len(sli)-2]),sli[:len(sli)-2])

    //删除开头 2 个元素
    fmt.Printf("len=%d cap=%d slice=%v\n",len(sli[2:]),cap(sli[2:]),sli[2:])

    //删除中间 2 个元素
    sli = append(sli[:3], sli[3+2:]...)
    fmt.Printf("len=%d cap=%d slice=%v\n",len(sli),cap(sli),sli)
}

operation result:

Recommended Reading

• Go - Array
• Go - variable declaration
• Go - Environment Installation

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