学生管理系统

linktable.h

class StudentInfo
{
public:
	char code[6];
	float chinesescore;
	float mathscore;
	StudentInfo* next;
	StudentInfo* prior;
};

//添加学生信息，如果prior为NULL，则newinfo为头结点
StudentInfo* AddInfo(StudentInfo* prior,StudentInfo* newinfo);
//根据编号删除学生信息
bool DelStudentInfo(char* code,StudentInfo*& pHead);
//根据编号查找学生信息
StudentInfo* FindStudentInfoByCode(char* code,StudentInfo* pHead);
//修改学生成绩信息
void ModifyStudentInfo(StudentInfo* p);
//从头结点开始打印学生信息
void PrintStudentInfo(StudentInfo* pHead);
//对指定的节点输入学生信息
void InputInfo(StudentInfo* pInfo);
//获取最后一个节点
StudentInfo* GetLastStudentInfo(StudentInfo* pHead);
//保存链表到文件，顺序保存
void SaveStudentInfoToFile(char* filename,StudentInfo* pHead);
//从文件中读取链表
void LoadStudentInfoFromFile(char* filename,StudentInfo*& pHead);
//操作提示
void ShowOperateInfo(void);

students.h

#include "linkTable.h"
#include <stdio.h>
#include <string.h>

//添加学生信息，如果prior为NULL，则newinfo为头结点
StudentInfo* AddInfo(StudentInfo* prior,StudentInfo* newinfo)
{
	if (!prior)
	{
		newinfo->next = NULL;
		newinfo->prior = NULL;
	}
	else
	{
		prior->next = newinfo;
		newinfo->prior = prior;
		newinfo->next = NULL;
	}
	memset(newinfo->code,0,sizeof(newinfo->code));
	InputInfo(newinfo);
	return newinfo;
}

//根据编号删除学生信息
bool DelStudentInfo(char* code,StudentInfo*& pHead)
{
	StudentInfo* pDel = FindStudentInfoByCode(code,pHead);
	if (pDel == NULL)
		return false;
	else
	{
		if (pDel == pHead)
			pHead = pDel->next;
		else
		{			
			pDel->prior->next = pDel->next;
			if (pDel->next != NULL)
				pDel->next->prior = pDel->prior;
		}
		delete pDel;
		pDel = NULL;
		return true;
	}
}

//根据编号查找学生信息
StudentInfo* FindStudentInfoByCode(char* code,StudentInfo* pHead)
{
	StudentInfo* p = pHead;
	while (p != NULL)
	{
		if (strcmp(p->code,code) == 0)
		{
			return p;
		}
		p = p->next;
	}
	return NULL;
}
//修改学生成绩信息
void ModifyStudentInfo(StudentInfo* p)
{
	printf("%s号学生当前信息：语文：%f，数学：%f\n",p->code,p->chinesescore,p->mathscore);
	printf("%s","请输入修改后的语文成绩：");
	scanf("%f",&(p->chinesescore));
	printf("%s","请输入修改后的数学成绩：");
	scanf("%f",&p->mathscore);
	printf("修改完毕，%s号学生最新信息：语文：%f，数学：%f\n",p->code,p->chinesescore,p->mathscore);
}

//从头结点开始打印学生信息
void PrintStudentInfo(StudentInfo* pHead)
{
	StudentInfo* p = pHead;
	while (p!=NULL)
	{
		printf("%s号学生：语文：%f，数学：%f\n",p->code,p->chinesescore,p->mathscore);
		p = p->next;
	}
}

//对指定的节点输入学生信息
void InputInfo(StudentInfo* pInfo)
{
	printf("%s","请输入学生编号：");
	scanf("%s",pInfo->code);
	printf("%s","请输入语文成绩：");
	scanf("%f",&pInfo->chinesescore);
	printf("%s","请输入数学成绩：");
	scanf("%f",&pInfo->mathscore);
}

//获取最后一个节点
StudentInfo* GetLastStudentInfo(StudentInfo* pHead)
{
	if (pHead == NULL)
		return NULL;
	StudentInfo* p = pHead;
	while (p)
	{
		if (p->next == NULL)
			return p;
		p = p->next;
	}
}

//保存链表到文件，顺序保存
void SaveStudentInfoToFile(char* filename,StudentInfo* pHead)
{
	FILE* f;
	f= fopen(filename,"w");
	StudentInfo* p = pHead;
	while (p)
	{
		fwrite(p->code,sizeof(char),sizeof(p->code),f);
		fwrite(&p->chinesescore,sizeof(float),1,f);
		fwrite(&p->mathscore,sizeof(float),1,f);
		//fwrite("\n",sizeof(char),1,f);
		p=p->next;
	}
	//fwrite("/0",sizeof(char),1,f);
	fclose(f);
}

//从文件中读取链表
void LoadStudentInfoFromFile(char* filename,StudentInfo*& pHead)
{
	FILE* f;
	f= fopen(filename,"r");
	if (f == NULL)
		return;
	fseek(f, 0, SEEK_SET); 
	StudentInfo* p = NULL;
	StudentInfo* newp = NULL;
	int c;
	//c = fgetc(f);
	while (!feof(f))
	{
		//因为不能完全依赖feof判断文件是否到结尾，所以用fgetc的返回值来判断，
		//当读取到结尾时，feof实际并没有获得到达结尾的信息，所以这里用fgetc继续读取一个字符，来判断是否结束
		//如果不是-1（结尾），那么回退一个文件位置，如果是-1，退出
		c = fgetc(f);
		if (c != -1)
			fseek(f, -1, SEEK_CUR);
		else
			return;
		if (pHead == NULL)
		{
			pHead = new StudentInfo;
			pHead->next = NULL;
			pHead->prior = NULL;
			memset(pHead->code,0,sizeof(pHead->code));
			fread(pHead->code,sizeof(char),sizeof(pHead->code),f);
			fread(&pHead->chinesescore,sizeof(float),1,f);
			fread(&pHead->mathscore,sizeof(float),1,f);
			p = pHead;
		}
		else
		{
			newp = new StudentInfo;
			newp->next = NULL;
			newp->prior = NULL;
			newp->prior = p;
			memset(newp->code,0,sizeof(newp->code));
			fread(newp->code,sizeof(char),sizeof(newp->code),f);
			fread(&newp->chinesescore,sizeof(float),1,f);
			fread(&newp->mathscore,sizeof(float),1,f);
			p->next = newp;
			p = newp;
		}	
		
	}
	fclose(f);
}

//操作提示
void ShowOperateInfo(void)
{
	printf("%s\n","1:增加信息");
	printf("%s\n","2:删除信息");
	printf("%s\n","3:查找信息");
	printf("%s\n","4:修改信息");
	printf("%s\n","5:保存信息");
	printf("%s\n","9:打印信息");
	printf("%s\n","0:结束");
}

main

#include "linkTable.h"
#include "stdio.h"
#include "stdlib.h"

int main()
{
	ShowOperateInfo();
	int i;
	//curInfo当前节点，用来添加节点用
	StudentInfo* curInfo = new StudentInfo;
	StudentInfo* pHead = NULL;	
	LoadStudentInfoFromFile("e://link.txt",pHead);
	//将curInfo指向最后一个节点
	if (pHead != NULL)
		curInfo = GetLastStudentInfo(pHead);
	char code[10]={0};
	while (true)
	{
		printf("%s","请输入操作号：");
		scanf("%d",&i);
		switch (i)
		{
			//退出
		case 0:
			exit(0);
			//添加
		case 1:
			if (pHead == NULL)
			{
				pHead = new StudentInfo;	
				curInfo = pHead = AddInfo(NULL,pHead);
			}
			else
			{
				StudentInfo* newInfo = new StudentInfo;
				curInfo = AddInfo(curInfo,newInfo);
			}
			break;
			//删除
		case 2:			
			printf("%s","请输入要删除的学生编号：");
			scanf("%s",code);
			DelStudentInfo(code,pHead);
			curInfo = GetLastStudentInfo(pHead);
			break;
			//查找
		case 3:
			printf("%s\n","请输入要查找的学生编号：");
			scanf("%s",code);
			{
				StudentInfo* p = FindStudentInfoByCode(code,pHead);
				if (p == NULL)
					printf("编号%s不存在",code);
				else
				{
					printf("%s号学生：语文：%f，数学：%f\n",p->code,p->chinesescore,p->mathscore);
				}
			}
			break;
			//修改
		case 4:
			printf("%s\n","请输入要修改的学生编号：");
			scanf("%s",code);
			{
				StudentInfo* p = FindStudentInfoByCode(code,pHead);
				if (p == NULL)
					printf("编号%s不存在",code);
				else
				{
					ModifyStudentInfo(p);
				}
			}
			break;
		case 5:
			SaveStudentInfoToFile("e://link.txt",pHead);
			break;
			//打印
		case 9:
			PrintStudentInfo(pHead);
			break;
		default:
			exit(0);
		}
	}
}