关于#链表#的问题：我试着写了一个链表插入的程序

我试着写了一个链表插入的程序，可是出处结果并没有我插入的那一段，请问为什么呢？

int main() {

void insert(stus * p);

stus *head;

stus student1 = {1, "liubei", 60, NULL};        //学生成绩初始化
stus student2 = {2, "zhangfei", 70, NULL};
insert(&student2);
stus student3 = {3, "guanyu", 80, NULL};

head = &student1;
student1.next = &student2;        //使三个结构相连
student2.next = &student3;
output(head);

}

void insert(stus *p) {

stus student_insert = {4, "caocao", 100, NULL};
student_insert.next = p->next;
p->next = &student_insert;

}