学生成绩管理系统链表实现

2016年7月11日18:02:51
链表的相关术语:
头结点:1.为什么需要头结点?
为了方便对链表的操作,因而需要头结点;
2.头结点是什么?
链表的第一个节点,首节点前面那节点,但该节点不保存有效数据;
首节点:首节点是链表中第一个保存有效数据的节点;
尾节点:尾节点是链表中最后一个保存有效数据的节点,该节点的指针域为空;
头指针:保存头结点地址的指针变量为头指针;
确定一个链表至少需要那几个参数?(或者说:如果要用一个函数来处理一个链表,那么该函数至少需要接受链表那几个参数)
确定一个链表只需要一个参数:头指针
这是因为,由链表的头指针可以找到链表的头结点,根据头结点的指针域可以找到链表的首节点,一直往后找知道找到链表的最后一个
节点,即尾节点,因此由头指针可以确定一个链表;
链表的创建是动态的分配内存还是静态的分配内存?
动态的分配内存:如果静态分配内存,那么一旦创建链表的函数执行完毕,那么系统就会自动释放静态内存空间,
而动态内存分配程序员可以通过编程来手动分配动态内存,也可以由程序员手动编程来释放动态内存.

#include<stdio.h>
#include<malloc.h>
#include<stdlib.h>

//学生基本信息结构体
typedef struct stu
{
long num;
char name[10];
float score;
}STUDENT;

//链表结构体
typedef struct node
{
STUDENT data;
struct node * pNext;
}SNODE;

//函数前置声明
SNODE * createList(SNODE * pHead, int len);//尾插法
SNODE * createList1(SNODE * pHead,int len);//头插法
void traverseList(SNODE * pHead);//遍历链表
void inputInfor(SNODE * pNew);//输入信息
SNODE * insertNode(SNODE * pHead,int pos);//插入节点
SNODE * deleteList(SNODE * pHead,int  pos);//删除节点
SNODE * initList(SNODE * pHead);//初始化链表
SNODE * locateElem(SNODE * pHead,long  num);//根据内容查找
SNODE * getElem(SNODE * pHead,int pos);//根据位置查找
int isEmpty(SNODE * pHead);//判断链表是否为空
void destroyList(SNODE * pHead);//销毁链表
void showMenu(void);//展示菜单

//初始化链表
SNODE * initList(SNODE * pHead)
{
pHead = (SNODE * )malloc(sizeof(SNODE));
if(NULL == pHead)
{
printf("动态内存分配失败!\n");
exit(-1);
}
pHead->pNext = NULL;
pHead->data.num = 0;
return pHead;
}

//判断链表是否为空,如果为空返回1,否则返回0
int isEmpty(SNODE * pHead)
{
if(NULL == pHead->pNext)
return 1;
else
return 0;
}

//求链表的长度,如果链表为空则返回0,非空则返回链表的长度
int getLength(SNODE * pHead)
{
SNODE * p;
int i = 0;
p = pHead->pNext;
/*if(1 == isEmpty(pHead))
return 0;
else*/
while(NULL != p)
{
p = p->pNext;
i++;
}
return i;
}

void destroyList(SNODE * pHead)//销毁链表
{
SNODE * pFree,* pCur;
pFree = pHead;
while(pFree)
{
pCur = pFree->pNext;
free(pFree);
pFree = pCur;
}
return ;
}

//展示菜单
void showMenu(void)
{
printf("___________________________________________\n");
printf("         欢迎使用学生成绩管理系统\n");
printf("\t    【1】创建学生信息\n");
printf("\t    【2】插入学生信息\n");
printf("\t    【3】删除学生信息\n");
printf("\t    【4】显示学生信息\n");
printf("\t    【5】查找学生信息\n");
printf("\t    【6】退出系统\n");
printf("___________________________________________\n\n");
return;
}

//动态的创建一个链表
SNODE * createList(SNODE * pHead, int len)
{
SNODE * pNew;
SNODE * pTail;
pTail = pHead;
int i;
for( i = 0;i<len;i++)
{
pNew = (SNODE * )malloc(sizeof(SNODE));
if(NULL == pNew)
{
printf("动态内存分配失败!\n");
exit(-1);
}
inputInfor(pNew);
pNew->pNext = NULL;
pTail->pNext = pNew;
pTail = pNew;
pHead->data.num ++;
}
return pHead;
}

//单链表的创建之尾插法
SNODE * createList1(SNODE * pHead,int len)
{
SNODE * pNew;
int i;
for(i = 0;i<len;i++)
{
pNew = (SNODE * )malloc(sizeof(SNODE));
if(NULL == pNew)
{
printf("动态内存分配失败!\n");
return NULL;
}
printf("请输入学生信息！\n");
printf("学号=");
scanf("%ld",&pNew->data.num);
printf("姓名=");
scanf("%s",pNew->data.name);
printf("分数=");
scanf("%f",&pNew->data.score);
/*if( NULL == pHead->pNext)
{
pNew->pNext = NULL;
pHead->pNext = pNew;
}
else
{
pNew->pNext = pHead->pNext;
pHead->pNext = pNew;
}
*/
pNew->pNext = pHead->pNext;
pHead->pNext = pNew;
}
return pHead;
}

//输入学生信息
void inputInfor(SNODE * pNew)
{
printf("请输入学生信息:\n");
printf("学号=");
scanf("%ld",&pNew->data.num);
printf("姓名=");
scanf("%s",pNew->data.name);
printf("分数=");
scanf("%f",&pNew->data.score);
return;
}

//学生结点的插入
SNODE * insertNode(SNODE * pHead,SNODE * cur,int pos)
{

SNODE * prev = pHead;
int i;
while(pos<1||pos>pHead->data.num+1)
{
return NULL;
}
for(i = 1;i<pos;i++)
{
prev = prev->pNext;
}
/*
if(prev->pNext==NULL)
{
cur->pNext = NULL;
prev->pNext = cur;
pHead->data.num ++;
}
else
{
cur->pNext = prev ->pNext;
prev->pNext = cur;
pHead->data.num++;
}
*/
cur->pNext = prev ->pNext;
prev->pNext = cur;
pHead->data.num++;
return pHead;
}

//学生结点的删除
SNODE * deleteNode(SNODE * pHead,int  pos ,SNODE * pDelete)
{
SNODE * prev;
SNODE * cur;
int i;
prev = pHead;
if(NULL == pHead->pNext)
{
printf("链表为空，不能删除元素!\n");
return NULL;
}
while(pos<1||pos>pHead->data.num)
{
return NULL;
}
for(i = 1;i<pos;i++)
{
prev = prev->pNext;
}
cur = prev->pNext;
/*if(NULL == cur->pNext )
{
prev->pNext = NULL;
*pDelete = *cur;
free(cur);
pHead->data.num--;
}
else
{
prev->pNext = cur->pNext;
*pDelete = *cur;
free(cur);
pHead->data.num--;
}
*/
prev->pNext = cur->pNext;
*pDelete = *cur;
free(cur);
pHead->data.num--;
return pHead;
}

//根据学生信息内容查找,查找成功返回元素指针,查找失败返回NULL;
SNODE *  locateElem(SNODE * pHead,long  num)
{
SNODE * p;
int pos = 0;
p = pHead->pNext;
/*if(NULL == pHead->pNext)
{
return 0;
}*/
while(NULL != p)
{
if(num == p->data.num)
{
return p;
}
p = p->pNext;
pos++;
}
return NULL;
}

//根据学生信息位置查找,查找成功返回元素指针,查找失败返回NULL;
SNODE *  getElem(SNODE * pHead,int pos)
{
SNODE * p;
int i = 1;
p = pHead->pNext;
/*if(p == NULL)
{
return NULL;
}*/
while(NULL != p&&i<pos)
{
p = p->pNext;
i++;
}
if(i == pos)
{
return p;
}
else
{
return NULL;
}
}

//链表的遍历
void traverseList(SNODE * pHead)
{
int i = 0;
SNODE * p = NULL;
p = pHead->pNext;
printf("        学号   姓名   分数 \n");
if(NULL == p)
{
printf("链表为空!\n");
}
else
{
while(NULL != p)
{
printf("第%d个学生   ",i+1);
printf("%-7ld%-7s%-6.2f\n",p->data.num,p->data.name,p->data.score);
p = p->pNext;
i++;
}
}
return;
}

//主函数
int main(void)
{
SNODE * pFound;
SNODE * pInsertNode;
SNODE pDeleteNode;
SNODE * pHead = NULL;
int len,pos,choice;

pHead = initList(pHead);//初始化链表
while(1)
{
showMenu();//展示链表的操作
printf("请输入您的选择:");
scanf("%d",&choice);
system("cls");
switch(choice)
{
case 1:printf("请输入原始班级中的人数:");
scanf("%d",&len);
pHead = createList(pHead,len);
system("cls");
printf("___________________________________________\n");
printf("     创建的学生信息显示\n");
traverseList(pHead);
printf("___________________________________________\n\n");
break;
case 2: pInsertNode = (SNODE * )malloc(sizeof(SNODE));
if(NULL == pInsertNode)
{
printf("动态内存分配失败!\n");
exit(-1);
}
inputInfor(pInsertNode);
while( NULL == insertNode(pHead,pInsertNode,pos))
{
printf("___________________________________________\n");
printf("     插入前学生信息显示\n");
traverseList(pHead);
printf("___________________________________________\n\n");
printf("请输入需要插入学生信息的位置:");
scanf("%d",&pos);
system("cls");
}
printf("___________________________________\n");
printf("     您需要插入学生显示\n");
printf("     学号   姓名   分数 \n");
printf("         %-7ld%-7s%-6.2f\n",pInsertNode->data.num,pInsertNode->data.name,pInsertNode->data.score);
printf("___________________________________\n\n");
printf("___________________________________________\n");
printf("        插入后学生信息显示\n");
traverseList(pHead);
printf("___________________________________________\n\n");
break;
case 3: while( NULL ==deleteNode(pHead,pos ,&pDeleteNode))
{
printf("___________________________________________\n");
printf("     删除前学生信息显示\n");
traverseList(pHead);
printf("___________________________________________\n\n");
printf("   请输入需要删除学生信息的位置:");
scanf("%d",&pos);
system("cls");
}
printf("___________________________________\n");
printf("     您需要删除学生显示\n");
printf("     学号   姓名   分数 \n");
printf("         %-7ld%-7s%-6.2f\n",pDeleteNode.data.num,pDeleteNode.data.name,pDeleteNode.data.score);
printf("___________________________________________\n");
printf("        删除后学生信息显示\n");
traverseList(pHead);
printf("___________________________________________\n\n");
break;
case 4: system("cls");
printf("___________________________________________\n");
printf("        该班级学生信息显示\n");
traverseList(pHead);
printf("___________________________________________\n\n");
break;
case 5: pos = 0;
while(pos<1)
{
printf("请输入您所需要查找元素的学号:\n");
scanf("%d",&pos);
system("cls");
}
//pFound = getElem(pHead,pos);
pFound = locateElem(pHead,pos);
if(NULL == pFound)
{
printf("查找失败!\n");
}
else
{
printf("_______________________________________\n");
printf("        学号   姓名   分数 \n");
printf("该学生的信息");
printf("%-7ld%-7s%-6.2f\n",pFound->data.num,pFound->data.name,pFound->data.score);
printf("_______________________________________\n\n");
}
break;
case 6:exit(0);
default:system("cls");
printf("您的操作有误!\n");
break;
}

}
return 0;
}