C语言链表实现班级管理系统

#include<stdio.h>
#include<stdlib.h>
#define M 20

//定义学生的结构体
typedef struct noab
{
int id;
char name[M];
char classroom[M];
float score;
struct node *next;
}student;
student *init()
{
student *p,*q,*head;
int i,a;
int n=0;
printf("输入学生信息的个数\n");
scanf("%d",&a);

head=NULL;
for(i=0;i<a;i++)
{
p=(student *)malloc(sizeof(student));
printf("输入第%d个学生的信息\n",i+1);
printf("学号:");
scanf("%d",&p->id);
printf("姓名：");
getchar();
gets(p->name);
printf("班级:");
gets(p->classroom);
printf("成绩:");
scanf("%f",&p->score);
n=n+1;
if(n==1)
{
head=p;
q=p;
q->next=NULL;

}else
{
q->next=p;
q=p;
p->next=NULL;
}
}
return head;
}
void display (student *head)
{
student *p=head;
while(p)
{
printf("学生的学号为%d，姓名为%s，班级为%s，分数为%f\n",p->id,p->name,p->classroom,p->score);
p=p->next;
}
}

student *addStudent(student *head)
{
student *p,*q;
q=head;
while(q->next) q=q->next;
p=(student *)malloc(sizeof(student));
printf("学号：");
scanf("%d",&p->id);
printf("姓名：");
getchar();
gets(p->name);
printf("班级:");
gets(p->classroom);
printf("成绩:");
scanf("%f",&p->score);
p->next=NULL;
q->next=p;
return head;
}

student *deleteStudent(student *head)
{
int a;
student *pre=NULL,*p;
printf("请输入要删除的id");
scanf("%d",&a);
if(!head) {printf("系统中已经没有数据可以删除\n");return head;}
p=head;
while(p&&p->id!=a)
{
pre=p;
p=p->next;
}
if(p)
{
if(!pre) head =head->next;
else pre->next=p->next;
free(p);
}
return head;

}

student *correctStudent(student *head)
{
int a;
student *p;
printf("请输入要修改的学生的id");
scanf("%d",&a);
if(!head) {printf("系统中已经没有数据可以修改\n");return head;}
p=head;
while(p&&p->id!=a)
{
p=p->next;
}
if(p==NULL){printf("没有查到要修改的学生的id\n");return head;}
else
{
printf("学号：");
scanf("%d",&p->id);
printf("姓名：");
getchar();
gets(p->name);
printf("班级:");
gets(p->classroom);
printf("成绩:");
scanf("%f",&p->score);
}
return head;
}
void writeFile(student *head)
{
FILE *outf;
student *p=head;
if((outf = fopen("data.txt","wb")) == NULL) {
printf("不能打开数据文件。\n");
exit(1);
}
while(p) {
fwrite(p,sizeof(student),1,outf);
p = p->next;
}
fclose(outf);
}

student *readFile(student *head)
{
int n=0;
student temp;
FILE *inf;
student *p=NULL,*q;
if((inf = fopen("data.txt","rb")) == NULL) {
printf("不能打开数据文件。\n");
exit(1);
}
while(fread(&temp,sizeof(student),1,inf)!=0)
{
p=(student *)malloc(sizeof(student));
p->id=temp.id;
p->score=temp.score;
strcpy(p->name,temp.name);
strcpy(p->classroom,temp.classroom);
n++;
if(n==1){head=p;q=p;}
else
{
q->next=p;
q=q->next;
}

}
q->next=NULL;
fclose(inf);
return head;
}

void main()
{
int a;
student *head,*p;
//head=init();
head=readFile(head);

do
{
printf("欢迎使用学生管理系统\n");
printf("1:增加学生\n2：删除学生\n3：修改信息\n4:显示所有信息\n5：退出系统\n");
printf("请输入您想进行的操作是：\n");
scanf("%d",&a);
switch(a)
{
case 1:head=addStudent(head);break;
case 2:head=deleteStudent(head);break;
case 3:head=correctStudent(head);break;
case 4:display(head);break;

}

}while(a != 5);
writeFile(head);

}