【C++】单链表实现学生成绩表系统

#include<iostream>
#include<string.h> 
#include <fstream>
#include"stdlib.h"
using namespace std;
class Node{
	public:
		int num;
		char name[20];
		float Math;
		float English;
		float Physics;
		float average;
		Node *next;
};
class StudList  
{  
private:  
    Node *head;                                                    //头节点  
public:  
    StudList();  
    void CreateList();                                                 //创建链表  
    void Display();                                                    //显示链表  
    int getlen() ;                                               //获取链表长度  
//  bool isEmpty();                                              //判断链表是否为空  
//  bool Find(const int n);                                      //在链表中查找某个值  
//  Node* GetNode(int i);                                        //返回第i个节点  
    Node *GetHead();
    
    void averGrade(Node *node);								//求平均成绩 
    void pushBack();                             	         //尾部添加一个学生 
    void Insert();                        		     //在第i个位置插入一个学生 
    int Delete();                               	  //删除一个个学生 
    int Modif();   		                        	 //修改一个个学生 的信息 
    void sort();								   	 //根据输入的参数决定使用某门课程成绩排序 
    void sortM();
    void sortE();
    void sortP();
    void sortAver();								//平均成绩排序 

    void CountNot();								//查询某一门学科不及格的人数和成绩单 
    int CountNotM();
    int CountNotE();
    int CountNotP();
};  

void menu(StudList *list); 
void Save(StudList *list);
void Read(StudList *list);

int main(){
	
	StudList list;
	list.CreateList();
	menu(&list);
	return 0;
}

StudList::StudList()  
{  
    head=new Node();  
    head->next=NULL;
} 

void StudList::Display(){
	Node *cur=head;
	int len = getlen();
	cout<<"len:"<<len<<endl;
	while(len--){
		cout<<"  学号："<<cur->num;
		cout<<"  姓名："<<cur->name;
		cout<<"  Math："<<cur->Math;
		cout<<"  English："<<cur->English;
		cout<<"  Physics："<<cur->Physics;
		cout<<"  平均成绩："<<cur->average<<endl;
		cur=cur->next;
	}
}

//建立一个空表 
void StudList::CreateList()  
{  
	head->num=0;
}

Node *StudList::GetHead(){
	return head;
}

void StudList::pushBack(){
	Node *cur,*p,*t;
	if(!head){
		head = new Node();	
	}
	cur=head;
	p=new Node();
	t= head;

	while(cur->next){
		cur=cur->next;
	}
	cout<<"输入学号："<<endl;
	cin>>p->num;
	while(t){
		if(t->num==p->num){
			cout<<"已存在该学号！"<<endl; 
			return;
		}
		t=t->next;
	}
	cout<<"输入姓名："<<endl;	
	cin>>p->name;
	cout<<"输入高数成绩："<<endl;
	cin>>p->Math;
	cout<<"输入英语成绩："<<endl;
	cin>>p->English;
	cout<<"输入物理成绩："<<endl;
	cin>>p->Physics;
	averGrade(p);
	if(head->num==0){
		head = p;
		return;
	}
	cur->next = p;
	p->next=NULL;
}


void StudList::averGrade(Node *node){
	node->average = (node->English+node->Math+node->Physics)/3;
}

//获取单链表长度 
int StudList::getlen(){
	int n=0;
	Node *cur;
	cur=head;
	while( cur ){
		n++;	
		cur=cur->next;
	}
	return n;
}

//插入一个节点 
void StudList::Insert(){
	int i,len;
	cout<<"输入要插入学生的位置(不能插入到第一个学生前和超过最后一个学生之后，即n>1，n<=len)：";
	cin>>i; 
	len=getlen();
	if(i<=2||i>len){
		
	}
	Node *cur,*t,*pr,*newNode;
	if(head==NULL||head->num==0){
		cout<<"当前表为空！"<<endl;
		StudList(); 
		return;
	}
	cur=head;
	pr = head;
	i-=1;		//这里的i根据情况来定，如果i表示的下标则不需要，表示位数则需要对i-1; 
	while(cur&&i--){
		pr=cur;
		cur=cur->next;	
	}
	newNode = new Node();
	t=head;							
	cout<<"输入插入学生的学号："<<endl;
	cin>>newNode->num;
		while(t){					//判断是否从在已有学号 
			if(t->num==newNode->num){
				cout<<"已存在该学号!"<<endl; 
				return;
			}
			t=t->next;
		}
	cout<<"输入姓名："<<endl;	
	cin>> newNode->name;
	cout<<"输入高数成绩："<<endl;
	cin>>newNode->Math;
	cout<<"输入英语成绩："<<endl;
	cin>>newNode->English;
	cout<<"输入物理成绩："<<endl;
	cin>>newNode->Physics;
	averGrade(newNode);
	
	pr->next=newNode;
	newNode->next=cur; 
	
}

//删除 
int StudList::Delete() {				//n表示学号 
	int n; 
	Node *cur,*pr;
	cur=head;
	pr=head;
	cout<<"输入要删除学生的学号：";
	cin>>n; 
	while(cur){
		if(cur->num==n){
			if(cur==head){			//如果删除的是头节点，直接令头节点为头节点的下一节点 
				head=head->next;
				return 1; 
			}
			pr->next=cur->next;
			return 1; 					//若删除的是最后一个节点则不能使用 cur->next->next,前边已经 cur = cur->next;不许操作 
		}
		pr=cur;
		cur=cur->next;
	}
	cout<<"没有查到要删除的学号"<<endl;
	return -1; 
}
 
 //修改指定学号学生的信息 
 int StudList::Modif(){			//n为学号 
	int a,n;	
	Node *cur;
	cur=head;
	cout<<"输入要修改学生的学号：";
	cin>>n; 
	while(cur){
		if(cur->num==n){
			cout<<"1.修改姓名"<<endl; 
			cout<<"2.修改数学成绩"<<endl; 
			cout<<"3.修改英语成绩"<<endl; 
			cout<<"4.修改物理成绩"<<endl; 
			cout<<"请输入要修改的项目(输入其它不做修改)：";
			cin>>a ;
			switch(a){
				case 1:
					cout<<"请输入修改姓名：";
					cin>>cur->name;
					return 1;
				case 2:
					cout<<"请输入修改的数学成绩：";
					cin>>cur->Math;
					return 1;
				case 3: 
					cout<<"请输入修改的英语成绩：";
					cin>>cur->English;
					return 1;
				case 4:
					cout <<"请输入修改的物理成绩：";
					cin>>cur->Physics;
					return 1;
				default:
					cout<<"退出修改"<<endl; 
					return 1;
			}
		}
		cur=cur->next;
	}
	return -1; 
}

void swapNode(Node *a,Node *b){			//交换两节点的信息 
	int temp;
	char c;
	float ft;
	
	temp=a->num;
	a->num=b->num;
	b->num=temp;
	
//姓名交换 
	for(int i=0;i<20;i++){
		c=a->name[i];
		a->name[i]=b->name[i];
		b->name[i]=c;
	}
		
	ft=a->Math;
	a->Math=b->Math;
	b->Math=ft;

	ft=a->English;
	a->English=b->English;
	b->English=ft;

	ft=a->Physics;
	a->Physics=b->Physics;
	b->Physics=ft;
	
	ft=a->average;
	a->average=b->average;
	b->average=ft;
}

void StudList::sortM(){			//按数学成绩排序 
	int len,inlen;
	Node *cur;
	len =getlen();
	while(--len){
		inlen = len;		
		cur = head;
		while(inlen--){
			if(cur->Math<cur->next->Math){
				swapNode(cur,cur->next);
			}
			cur=cur->next;
		}
	}
}

void StudList::sortE(){			//按英语成绩排序 
	int len,inlen;
	Node *cur;
	cur=head;
	len =getlen();
	while(--len){
		inlen = len;		
		cur = head;
		while(cur&&inlen--){
			if(cur->English<cur->next->English){
				swapNode(cur,cur->next);
			}
			cur=cur->next;
		}
	}	
}

void StudList::sortP(){				//按物理成绩排序 
	int len,inlen;
	Node *cur;
	cur=head;
	len =getlen();
	while(--len){
		inlen = len;		
		cur = head;
		while(cur&&inlen--){
			if(cur->Physics<cur->next->Physics){
				swapNode(cur,cur->next);
			}
			cur=cur->next;
		}
	}	
}

void StudList::sortAver(){
	int len,inlen,rank=1;
	Node *cur;
	cur=head;
	len =getlen();
	while(--len){
		inlen = len;		
		cur = head;
		while(cur&&inlen--){
			if(cur->average<cur->next->average){
				swapNode(cur,cur->next);
			}
			cur=cur->next;
		}
	}
	cur=head;
	while(cur){
		cout<<"学号："<<cur->num<<" 姓名："<<cur->name<<"  数学成绩："<<cur->Math<<"  英语成绩："<<cur->English 
		<<"  物理成绩："<<cur->Physics<<"  平均成绩："<<cur->average<<" 名次："<<rank<<endl; 
		if(cur->next&&cur->average==cur->next->average){
			cur=cur->next;
			continue;		
		}
		rank++;
		cur=cur->next;	
	}
}

//按成绩排序 
void StudList::sort(){
	int m;
	cout<<"1.按数学成绩排序。"<<endl;
	cout<<"2.按英语成绩排序。"<<endl;
	cout<<"3.按物理成绩排序。"<<endl;
	cout<<" 选择某一门排序方式："; 
	cin>>m;
	switch(m){
		case 1:
			sortM();
			break;
		case 2:
			sortE();
			break;
		case 3:
			sortP();
			break;
		default :
			break;
	}
}

int StudList::CountNotM(){
	int n=0;
	Node *cur;
	cur = head;
	while(cur){
		if(cur->Math<60){
			cout<<"学号："<<cur->num<<" 姓名："<<cur->name<<" 成绩："<<cur->Math<<endl; 
			n++;
		}
		cur=cur->next;
	}
	cout<<"共计数学不及格人数："<<n<<endl;
	return n;
}

int StudList::CountNotE(){
	int n=0;
	Node *cur;
	cur = head;
	while(cur){
		if(cur->English<60){
			cout<<"学号："<<cur->num<<" 姓名："<<cur->name<<" 成绩："<<cur->English<<endl; 
			n++;
		}
		cur=cur->next;
	}
	cout<<"共计英语不及格人数："<<n<<endl;
	return n;	
}


int StudList::CountNotP(){
	int n=0;
	Node *cur;
	cur = head;
	while(cur){
		if(cur->Physics<60){
			cout<<"学号："<<cur->num<<" 姓名："<<cur->name<<" 成绩："<<cur->Physics<<endl; 
			n++;
		}
		cur=cur->next;
	}
	cout<<"共计物理不及格人数："<<n<<endl;
	return n;	
}

//统计不及格成绩名单 
void StudList::CountNot(){
	int m;
	cout<<"1.统计数学成绩不及格名单。"<<endl;
	cout<<"2.统计英语成绩不及格名单。"<<endl;
	cout<<"3.统计物理成绩不及格名单。"<<endl;
	cout<<"输入选择方式：";
	cin>>m; 
	switch(m){
		case 1:
			CountNotM();
			break;
		case 2:
			CountNotE();
			break;
		case 3:
			CountNotP();
			break;
		default :
			break;
	}
}

//菜单 
void menu(StudList *list){
	int a; 
	cout<<"************************************"<<endl;
	cout<<"**   欢迎使用学生成绩表管理系统   **"<<endl; 
	cout<<"************************************"<<endl;
	while(1){
		
		system("pause");
		system("cls");
		cout<<"********************************"<<endl;
		cout<<"*  1.添加一个学生成绩。        *"<<endl;
		cout<<"*  2.删除一个学生成绩。        *"<<endl;
		cout<<"*  3.修改一个学生成绩。        *"<<endl;
		cout<<"*  4.插入一个学生成绩。        *"<<endl;
		cout<<"*  5.显示学生成绩表。          *"<<endl;
		cout<<"*  6.按某一课成绩排序。        *"<<endl;
		cout<<"*  7.统计某一课成绩不及格人数。*"<<endl;
		cout<<"*  8.平均成绩排名。            *"<<endl;
		cout<<"*  9.打开本地成绩表。          *"<<endl;
		cout<<"*  10.按其它键退出并保存。     *"<<endl; 
		cout<<"********************************"<<endl;
		cin>>a;
		switch(a){
			case 1:
				list->pushBack();
				break;
				
			case 2:
				list->Display();
				list->Delete();
				list->Display();
				break;
				
			case 3:
				list->Display();
				list->Modif();
				list->Display();
				break;
				
			case 4:
				list->Display();
				list->Insert();
				list->Display();
				break;	
			case 5:
				list->Display();
				break;
	
			case 6:
				list->sort();
				list->Display();
				break;
				
			case 7:
				list->CountNot();
				break;
				
			case 8:
				list->sortAver();
				break;
				
			case 9:
				Read(list);
				break;
				
			default:
				Save(list);
				return;

		}	
	}
}

//保存文件 
void Save(StudList *list)
{
	Node *p;
	ofstream outfile;
	p=list->GetHead();
    
	outfile.open("Stud_data.dat",ios::binary);   
	    if(!outfile){
			cerr<<"open error!"<<endl; 
			return; 
		}
		while(p){
			outfile.write((char *)p,sizeof(Node)); 
			p=p->next;
		}
        outfile.close();   
	    cout<<"保存成功！"<<endl;
} 

//读文件 
void Read(StudList *list)
{
	Node *p,*q,*h;
	ifstream infile; 
	list->CreateList();
	p=list->GetHead();
	infile.open("Stud_data.dat",ios::binary);   
    if(!infile)
    {
 	  	cerr<<"open error!"<<endl;
		return; 
	}
	while(!infile.eof()){
		infile.read((char *)p,sizeof(Node));
		q= new Node();
		p->next = q;
		p=q;
	}
    h=list->GetHead();	
	while(h->next->num){
		h=h->next;
	}
	h->next=NULL;
    infile.close();  
    cout<<"读取成功！"<<endl;
}