package main

import (
    "log"
    "sort"
)

type Stu struct {
    id   int
    name string
}

var class []*Stu

type ByID []*Stu

func (s ByID) Len() int {
    return len(s)
}
func (s ByID) Swap(i, j int) {
    s[i], s[j] = s[j], s[i]
}
func (s ByID) Less(i, j int) bool {
    return s[i].id < s[j].id
}

type ByName []*Stu

func (s ByName) Len() int {
    return len(s)
}
func (s ByName) Swap(i, j int) {
    s[i], s[j] = s[j], s[i]
}
func (s ByName) Less(i, j int) bool {
    return s[i].name < s[j].name
}

func NewDemoClass() {
    stu1 := &Stu{11, "huang"}
    stu2 := &Stu{2, "jian"}
    stu3 := &Stu{33, "ping"}
    stu4 := &Stu{4, "ao"}
    stu5 := &Stu{5, "lili"}

    class = append(class, stu1)
    class = append(class, stu2)
    class = append(class, stu3)
    class = append(class, stu4)
    class = append(class, stu5)
}

func showClass() {
    for _, v := range class {
        log.Println(*v)
    }
}

func main() {
    NewDemoClass()

    sort.Sort(ByID(class))
    showClass()
    log.Println()

    sort.Sort(ByName(class))
    showClass()
    log.Println()
}

package main

import (
    "log"
    "sort"
)

type Stu struct {
    id   int
    name string
}

var class []Stu

type ByID []Stu

func (s ByID) Len() int {
    return len(s)
}
func (s ByID) Swap(i, j int) {
    s[i], s[j] = s[j], s[i]
}
func (s ByID) Less(i, j int) bool {
    return s[i].id < s[j].id
}

type ByName []Stu

func (s ByName) Len() int {
    return len(s)
}
func (s ByName) Swap(i, j int) {
    s[i], s[j] = s[j], s[i]
}
func (s ByName) Less(i, j int) bool {
    return s[i].name < s[j].name
}

func NewDemoClass() {
    stu1 := Stu{11, "huang"}
    stu2 := Stu{2, "jian"}
    stu3 := Stu{33, "ping"}
    stu4 := Stu{4, "ao"}
    stu5 := Stu{5, "lili"}

    class = append(class, stu1)
    class = append(class, stu2)
    class = append(class, stu3)
    class = append(class, stu4)
    class = append(class, stu5)
}

func showClass() {
    for _, v := range class {
        log.Println(v)
    }
}

func main() {
    NewDemoClass()

    sort.Sort(ByID(class))
    showClass()
    log.Println()

    sort.Sort(ByName(class))
    showClass()
    log.Println()
}

package main

import (
    "fmt"
    "sort"
)

type Shop struct {
    Price float32
    Date  string
}

type ByPriceData []Shop

func (s ByPriceData) Len() int {
    return len(s)
}

func (s ByPriceData) Swap(i, j int) {
    s[i], s[j] = s[j], s[i]
}

func (s ByPriceData) Less(i, j int) bool {
    if s[i].Price > s[j].Price {
        return true
    } else if s[i].Price == s[j].Price {
        return s[i].Date < s[j].Date
    } else {
        return false
    }
}

func main() {

    shops := []Shop{
        {1, "222"}, {7, "222"}, {3, "222"},
        {4, "222"}, {5, "2018/1/21"}, {5, "2018/1/20"},
        {5, "2018/1/16"}, {5, "2018/1/19"},
        }

    sort.Sort(ByPriceData(shops))

    fmt.Println(shops)
}