举两个例子，说明 sort.Interface实现多级排序。
例子 1
学生成绩排序（先按成绩降序，成绩相同按姓名升序）
package main import ( "fmt" "sort" ) type Student struct { Name string Score int } type ByScoreAndName []Student func (s ByScoreAndName) Len() int { return len(s) } func (s ByScoreAndName) Swap(i, j int) { s[i], s[j] = s[j], s[i] } func (s ByScoreAndName) Less(i, j int) bool { // 第一级：按分数降序（分数高的排前面） if s[i].Score != s[j].Score { return s[i].Score > s[j].Score } // 第二级：分数相同时，按姓名升序 return s[i].Name < s[j].Name } func main() { students := []Student{ {"Alice", 85}, {"Bob", 90}, {"Charlie", 85}, {"David", 90}, } sort.Sort(ByScoreAndName(students)) for _, s := range students { fmt.Printf("%s: %d\n", s.Name, s.Score) } // 输出: // Bob: 90 // David: 90 // Alice: 85 // Charlie: 85 }例子 2
员工排序（先按部门升序，部门相同按工资降序，工资相同按工号升序）
package main import ( "fmt" "sort" ) type Employee struct { ID int Department string Salary float64 } type ByDeptSalaryID []Employee func (e ByDeptSalaryID) Len() int { return len(e) } func (e ByDeptSalaryID) Swap(i, j int) { e[i], e[j] = e[j], e[i] } func (e ByDeptSalaryID) Less(i, j int) bool { // 第一级：按部门升序 if e[i].Department != e[j].Department { return e[i].Department < e[j].Department } // 第二级：部门相同时，按工资降序 if e[i].Salary != e[j].Salary { return e[i].Salary > e[j].Salary } // 第三级：工资相同时，按工号升序 return e[i].ID < e[j].ID } func main() { employees := []Employee{ {103, "Engineering", 75000}, {101, "Engineering", 80000}, {102, "Engineering", 80000}, {201, "Sales", 70000}, {202, "Sales", 75000}, } sort.Sort(ByDeptSalaryID(employees)) for _, emp := range employees { fmt.Printf("ID: %d, Dept: %s, Salary: %.2f\n", emp.ID, emp.Department, emp.Salary) } // 输出: // ID: 101, Dept: Engineering, Salary: 80000.00 // ID: 102, Dept: Engineering, Salary: 80000.00 // ID: 103, Dept: Engineering, Salary: 75000.00 // ID: 202, Dept: Sales, Salary: 75000.00 // ID: 201, Dept: Sales, Salary: 70000.00 }
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