信息管理（单链表）

······················对单链表的学习总结·····················

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

typedef int ElemType;

typedef struct Node
{
char name[20];  //名字
int num; //学号
int CH;      //语文
int MA;      //数学
int EN;      //英语
struct Node *next;
}Node;

Node * NewLink(int n) //头插法建立新表
{
Node *p, *h;
int i;
h = NULL;
for (i = 0; i < n; i++)
{
if ((p = (Node *)malloc(sizeof(Node))) == NULL)
{
printf("不能分配空间！");
exit(0);
}
p->next = h;
h = p;
printf("\n请输入第%d位学生姓名:", i + 1);
scanf("%s",p->name);
printf("\n请输入学号:");
scanf("%d", &p->num);
printf("\n请输入语文成绩:");
scanf("%d", &p->CH);
printf("\n请输入数学成绩:");
scanf("%d", &p->MA);
printf("\n请输入英语成绩:");
scanf("%d", &p->EN);

}
if (h != NULL)
printf("申请成功！");
return (h);
}

Node * CreateList_End(int n)  //尾插法，头结点为NULL
{
Node *head, *p, *e;
int i;

head = (Node *)malloc(sizeof(Node));
e = head;     //让e指向头结点
for(i=0;i<n;i++)
{
p = (Node*)malloc(sizeof(Node));
printf("\n请输入第%d位学生姓名:", i + 1);
scanf("%s", p->name);
printf("\n请输入学号:");
scanf("%d", &p->num);
printf("\n请输入语文成绩:");
scanf("%d", &p->CH);
printf("\n请输入数学成绩:");
scanf("%d", &p->MA);
printf("\n请输入英语成绩:");
scanf("%d", &p->EN);
e->next = p;     //把新结点添加到表尾  
e = p;           //把指针指向新结点
}      
e->next = NULL; //尾结点的指针域置空

return head;               
}

Node * search(Node * head, char *name) //对单个元素进行查找
{
Node *p;
char *y;
p = head->next;
while (p != NULL)
{
y = p->name;
if (strcmp(y, name) == 0)
{
printf("姓名：%s\n", p->name);
printf("\n学号: %d\n", p->num);
printf("\n 语文:%d  数学:%d  英语:%d\n",p->CH,p->MA,p->EN);
return (p);
}
else p = p->next;
}
if (p == NULL)
printf("没有查找到该数据！");
return 0;
}


void insert(Node *head)  //头插法插入新信息
{
Node *p,*s;
char x[20];
char *y;
p = head->next;        //p=head的头结点
while (p != NULL)
{
printf("名字：%s学号：%d语文：%d数学：%d英语：%d\n", p->name, p->num, p->CH, p->MA, p->EN);
p = p->next;     //指向下一个结点
}
printf("\n请问在那位学生的后面插入信息：");
scanf("%s",x);
s = (Node *)malloc(sizeof(Node));
while (p != NULL)
{
y = p->name;
if (strcmp(y,x)==0)        //在x同学的后面插入信息
{
printf("\n请输入你要插入的信息!");
printf("\n请输入学生姓名:");
scanf("%s", &p->name);
printf("\n请输入学生学号:");
scanf("%d", &p->num);
printf("\n请输入语文成绩:");
scanf("%d", &p->CH);
printf("\n请输入数学成绩:");
scanf("%d", &p->MA);
printf("\n请输入英语成绩:");
s->next = p->next;
p->next = s;
}
else p = p->next;
}
}

Node * search2(Node *h,char  *x)   //求出当前结点的前驱结点
{
Node *p, *s;
char *y;
p = h->next;
s = h;
while (p != NULL)
{
y = p->name;
if (strcmp(y,x) == 0)
return(s);
else
{
p = p->next;
s = s->next;
}
}
if (p == NULL)
printf("没有查找到数据!");
return 0;
}

void del(Node *x, Node *y)  //删除结点
{
Node *s;
s = y;
x->next = y->next;
free(s);
}

void change(Node * head,char *x)
{
Node *p = head->next;
char *y;
while (p != NULL)
{
y = p->name;
if (strcmp(y, x) == 0)
{
printf("\n请输入你要修改的信息!");
printf("\n请输入学生姓名:");
scanf("%s", &p->name);
printf("\n请输入学生学号:");
scanf("%d", &p->num);
printf("\n请输入语文成绩:");
scanf("%d", &p->CH);
printf("\n请输入数学成绩:");
scanf("%d", &p->MA);
printf("\n请输入英语成绩:");
}
else p = p->next;
}
}

int main()
{
int n;
Node *head, *searchpoint,*forepoint;  //searchpoint为前驱结点，forepoint为当前结点
char name[20];

printf("需要录入多少位同学的信息：");
scanf("%d", &n);
//head = NewLink(n);  //建立初始化函数
head = CreateList_End(n);
system("cls");
while (1)
{

printf("\t\t\t1)查找信息\n\n");
printf("\t\t\t2)修改信息\n\n");
printf("\t\t\t3)删除信息\n\n");
printf("\t\t\t4)增加信息\n\n");
printf("\n请输入要要执行的命令: ");
scanf("%d", &n);
if (n == 1)
{
printf("\n请输入你要查找的人的姓名：");
scanf("%s", &name);
search(head, name);
system("cls");
}
else if (n == 2)
{
printf("\n请输入要更改的学生信息：");
scanf("%s", &name);
change(head, name);
system("cls");
}
else if (n == 3)
{
printf("\n请输入你要删除的人的信息：");
scanf("%s", &name);
forepoint = search(head, name);
searchpoint = search2(head, name);
del(searchpoint, forepoint);
system("cls");
}
else if (n == 4)
{
printf("\n请输入要增加的信息：\n");
insert(head);
system("cls");
}
}
}