C++ set 多级排序 多维度排序

#include <iostream>
#include <set>
#include <algorithm>
using namespace std;

/*Student结构体*/
struct Student {
  string  name;
  int id;
  int score;
};

/*“仿函数"。为Student set指定排序准则*/
class studentSortCriterion {
public:
  /*类型要与set容器类型一致*/
  bool operator()( const Student *a, const Student *b ) const
  {
    // 成绩相等，按照id从小到大排；成绩不相等，按照成绩从大到小排
    return( (a->score == b->score) ? (a->id < b->id) : (a->score > b->score) );
  }
};


int main()
{
  set<Student*, studentSortCriterion> stuSet;
  set<Student*> stus;

  Student stu1, stu2, stu3;
  stu1.name = "张三";
  stu1.id   = 1;
  stu1.score  = 100;

  stu2.name = "李四";
  stu2.id   = 2;
  stu2.score  = 90;

  stu3.name = "小明";
  stu3.id   = 3;
  stu3.score  = 100;

  stuSet.insert( &stu1 );
  stuSet.insert( &stu2 );
  stuSet.insert( &stu3 );

  /* 查找 */
  Student stuTem;
  stuTem.score  = 100;
  stuTem.id = 3;
  Student           * stuTempPtr;
  set<Student*, studentSortCriterion>::iterator iter;
  iter = stuSet.find( &stuTem );
  if ( iter != stuSet.end() )
  {
    cout << (*iter)->name << endl;
  }

  else {
    cout << "Cannot find the student!" << endl;
  }


  /* 遍历 */
  for ( std::set<Student*, studentSortCriterion>::iterator it = stuSet.begin(); it != stuSet.end(); it++ )
  {
    std::cout << (*it)->name << endl;
  }
}

上面程序会根据学生ID先进行排名然后再根据分数进行排名，排序准则需要满足以下要求，摘自C++标准库第二版：

输出结果：

​​c++ set容器排序准则 - 每天一点积累 - 博客园​​