C 语言函数指针在实现面向对象编程中的多态性的作用？

returnType (*functionPointerName)(parameterList);

struct Undergraduate {
  int roll_no;
  char *name;
  float gpa;
};

struct Graduate {
  int roll_no;
  char *name;
  char *research_area;
};

// 获取学生信息
float getStudentInfo(void *student, char info_type) {
  float result = 0.0;
  switch (info_type) {
    case 'r':
      result = ((Undergraduate *)student)->roll_no;
      break;
    case 'n':
      result = ((Undergraduate *)student)->name;
      break;
    case 'g':
      result = ((Undergraduate *)student)->gpa;
      break;
    case 'a':
      result = ((Graduate *)student)->research_area;
      break;
  }
  return result;
}

// 主函数
int main() {
  Undergraduate undergrad = {1, "John", 3.8};
  Graduate grad = {2, "Mary", "Computer Science"};

  // 创建函数指针
  float (*getStudentInfoPtr)(void *, char);

  // 为本科生设置函数指针
  getStudentInfoPtr = getStudentInfo;

  // 打印本科生信息
  printf("Undergraduate:\n");
  printf("Roll No: %.2f\n", getStudentInfoPtr(&undergrad, 'r'));
  printf("Name: %s\n", getStudentInfoPtr(&undergrad, 'n'));
  printf("GPA: %.2f\n\n", getStudentInfoPtr(&undergrad, 'g'));

  // 为研究生设置函数指针
  getStudentInfoPtr = getStudentInfo;

  // 打印研究生信息
  printf("Graduate:\n");
  printf("Roll No: %.2f\n", getStudentInfoPtr(&grad, 'r'));
  printf("Name: %s\n", getStudentInfoPtr(&grad, 'n'));
  printf("Research Area: %s\n", getStudentInfoPtr(&grad, 'a'));

  return 0;
}