}

如menu()函数所示，该系统一共有7个功能

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

struct emp{
	int id;
	char name[50];
	struct emp * next;
//	struct emp * prev;
};

struct emp * initList();

struct emp * addListTailNode(struct emp * head);

struct emp * deleteListNode(struct emp * head,int id);

struct emp * searchEmp(struct emp * head,int id);

int printList(struct emp * l);

int printNode(struct emp * p);

struct emp * sortList(struct emp * head);

int getListLen(struct emp * head);

int writeToDisk(struct emp * head);

struct emp * readFromDisk();

int menu();

int usage(struct emp * head);

#include "emp.h"

int main(){
	struct emp * head;
	head=readFromDisk();
	usage(head);
	return 0;
}

struct emp * initList(){
	struct emp * head;
	head=(struct emp *)malloc(sizeof(struct emp));
	head->next=NULL;
	return head;
}

struct emp * addListTailNode(struct emp * head){  
	int id;  
	char name[50];   
	struct emp * p, * last , * check;  
	last = head;  
	while(last->next!=NULL){  
		last=last->next;  
	}  
	printf("依次输入：员工id号，姓名!\n");  
	scanf("%d%s",&id,&name);  
	check = head;  
	while(check!=last){  //遍历 
		check=check->next;
		if(id==check->id){  
			printf("添加失败！员工id号重复！\n");  
			return head;  
		}  
	}  
	p=(struct emp *)malloc(sizeof(struct emp));   
	p->id=id;  
	strcpy(p->name,name);  
	//
	last->next=p;    
	last=p;    
	p->next=NULL;  
	printf("%s员工信息已添加!\n",p->name);  
	return head;  
}  

struct emp * deleteListNode(struct emp * head,int id){  
	struct emp * p,* q;  
	p = head->next;  
	while(p!=NULL){  
		if(p->next->id==id){  
			break;  
		}  
		p=p->next;  
	}  
	if(head->next==NULL){  
		printf("书籍信息为空！删除失败！\n");  
	}  
	else{    
		q = p->next;
		p->next = q->next;
		printf("%s书籍信息被删除！\n",q->name); 
		free(q);  
	}  
	return head;  
}  

struct emp * searchEmp(struct emp * head,int id){//查询，返回节点信息  
	struct emp * p;  
	p = head->next;  
	while(p!=NULL){  
		if(p->id==id){  
			break;  
		}  
		p=p->next;  
	}  
	return p;  
} 

int printNode(struct emp * p){//打印节点信息  
	if(p!=NULL){  
		printf("员工id: %d    员工姓名：%s\n",p->id,p->name);  
	}  
	else{  
		printf("系统内无该员工信息！\n");  
	}  
	return 0;  
}  

int printList(struct emp * head){  //打印整条链表
	struct emp * p;  
	p = head->next;  
	while(p!=NULL){  
		printNode(p);  
		p=p->next;  
	}  
	return 0;  
}  

struct emp * sortList(struct emp * head){//排序
	struct emp * p,* q;
	int temp_id;
	char temp_name[50];
	for(p=head->next;p!=NULL;p=p->next){
		for(q=p->next;q!=NULL;q=q->next){
			if(p->id>q->id){
				temp_id = q->id;
				q->id = p->id;
				p->id = temp_id;
				//
				strcpy(temp_name,q->name);
				strcpy(q->name,p->name);
				strcpy(p->name,temp_name);
			}
		}
	}
	return head;
}

int getListLen(struct emp * head){
	int len=0;
	struct emp * p;
	p=head->next;
	while(p!=NULL){
		len++;
		p=p->next;
	}
	return len;
}

int writeToDisk(struct emp * head){
	FILE * fp;
	struct emp * p;
	if((fp = fopen("D:\\emp.hhtx", "w")) == 0){
		printf("写入失败……!\n");
		return 0;
	}
	//
	p=head->next;
	while(p!=NULL){
		fwrite(p,sizeof(struct emp),1,fp);
		printf("%d  %s\n",p->id,p->name);
		p=p->next;
	}
	fclose(fp);
	return 0;
}

struct emp * readFromDisk(){
	FILE * fp;  
	struct emp * head,* last,* p,* temp;
	head = initList();
	if((fp = fopen("D:\\emp.hhtx", "r")) == 0){
		printf("加载失败……未找到存档数据!\n\n");
		return head;
	}
	//
	last = head;  
	p=(struct emp *)malloc(sizeof(struct emp));  
	while(p!=NULL){
		p=(struct emp *)malloc(sizeof(struct emp));  
		fread(p,sizeof(struct emp),1,fp);
		printf("读取数据: %d  %s\n",p->id,p->name); 
		//
		last->next=p;    
        last=p;    
		p=p->next;
	}
	fclose(fp);
	printf("系统数据初始化完成！");
	return head;
}

int menu(){
	printf("请按提示输入完成操作！\n");  
	printf("1.查询员工信息\n");  
	printf("2.统计员工数量\n");  
	printf("3.录入员工信息\n");  
	printf("4.删除员工信息\n");  
	printf("5.按id排序所有员工\n"); 
	printf("6.打印所有员工信息\n");
	printf("7.退出系统\n");   
	return 0;
}

int usage(struct emp * head){
	int x,id;   
	struct emp * p;
	menu();
	while(1){  
		printf("请输入序列号：");  
		scanf("%d",&x);  
		switch(x){  
		case 1:  
			printf("输入所要查询的员工的id号：");  
			scanf("%d",&id);  
			p = searchEmp(head,id);  
			printNode(p);  
			printf("---------------------------------\n");  
			break; 
		case 2:
			printf("系统中一共存在%d个员工\n",getListLen(head));
			break;
		case 3:   
			head=addListTailNode(head);  
			printf("---------------------------------\n");  
			break;  
		case 4:  
			printf("输入所要删除的员工的id号：");  
			scanf("%d",&id);  
			head=deleteListNode(head,id);  
			printf("---------------------------------\n");  
			break; 
		case 5:
			printf("排序开始……\n");
			head=sortList(head);
			printf("排序已完成！\n");
			printf("---------------------------------\n");  
			break;
		case 6:  
			printList(head);  
			printf("---------------------------------\n");  
			break;  
		case 7:    
			writeToDisk(head);
			printf("保存完成……\n");
			printf("已退出系统!\n");  
			printf("---------------------------------\n"); 
			return 0; 
		default:
			return 0;  
		}  
	}  
	return 0;
}