c版的回调函数与c++版的虚函数

C语言的回调函数思想代码：
#include <stdio.h>
void *max(void *base, unsigned int nmemb, unsigned int size,
    int (*compar)(const void *, const void *))
{
    int i;
    void* max_data = base;
    char* tmp = base;
    for (i=1; i<nmemb; i++) {
        tmp = tmp + size;
        if (compar(max_data, tmp) < 0) {
            max_data = tmp;
        }
    }
    return max_data;
}
int compar_int(const void* x, const void* y)
{
    return (*(int*)x - *(int*)y);
}
typedef struct _Student {
    char name[16];
    int score;
} Student;
int compar_student(const void* x, const void* y)
{
    return (((Student*)x)->score - ((Student*)y)->score);
}
int main()
{
    int data_int[] = {3, 2, 56, 41, 22, 7};
    unsigned int count_int = sizeof(data_int) / sizeof(int);
    int* max_int = (int*)max(data_int, count_int, sizeof(int), &compar_int);
    printf("max int: %d\n", *max_int);
    Student data_student[] = {
        {"Kate", 92},
        {"Green", 85},
        {"Jet", 77},
        {"Larry",88},
    };
    unsigned int count_student = sizeof(data_student) / sizeof(Student);
    Student* high_score = (Student*)max(data_student,
        count_student, sizeof(Student), &compar_student);
    printf("high score -- name:%s, score:%d\n", high_score->name, high_score->score);