看不懂 求帮助~

#include "stdio.h"
#include "stdlib.h"
struct stu
{
     int index;
     float score;
     struct stu *next;
};
void CreateList(struct stu *head)
{
     struct stu *temp=head;                          //将头指针赋给一个临时变量
     int i=1;
     printf("请输入5位学生的成绩：\n");
     while(i<=5)
{
         struct stu *newNode=(struct stu*)malloc(sizeof(struct stu));   //为新结点分配空间
         newNode->next=NULL;                                     //新节点next域赋值为NULL
         newNode->index=i++;                                     //为新结点赋值
         scanf("%f",&newNode->score);
         temp->next=newNode;                                     //将新结点连到链表末尾
         temp=newNode;                                         //修改临时指针指向新结点
     }
}
void main()
{
     struct stu *head;
     head=(struct stu*)malloc(sizeof(struct stu));                         //为头结点分配空间
     head->next=NULL;                                             //头节点next域赋值为NULL
     CreateList(head);
}
谁能给我讲讲中间函数 具体是怎么运行的啊