stl中重载<操作符的时候需要比较类中的多个字段

#include <algorithm>
#include <iostream>
#include <iomanip>

using std::cout;
using std::endl;

struct Student
{
public:
    int iGrade1;
    int iGrade2;
    int iGrade3;

    bool operator < (const Student& other) const
    {
        return (iGrade1 < other.iGrade1) || (!(other.iGrade1 < iGrade1) && (iGrade2 < other.iGrade2))
                || (!(other.iGrade2 < iGrade2) && iGrade3 < other.iGrade3);
    }

};

void Print(Student* pStu, int iCount)
{
    if (NULL == pStu)
    {
        return;
    }

    for(int i = 0; i < iCount; ++i)
    {
        cout << pStu[i].iGrade1 << "\t" << pStu[i].iGrade2 << "\t" << pStu[i].iGrade3 << endl;
    }
}

int _tmain(int argc, _TCHAR* argv[])
{
    Student stus[] = { {100, 100, 100}, {100, 100, 90}, {100, 100, 80}, {100, 100, 99}, {100, 100, 50},
                      {100, 80, 100}, {100, 80, 60}, {10, 10, 100}, {10, 30, 100}, {100, 70, 60},
                       {100, 70, 100}, {100, 60, 60}, {86, 10, 100}, {77, 30, 100}, {76, 70, 60}, };

    std::sort(stus, stus + _countof(stus));

    Print(stus, _countof(stus));

    return 0;
}