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#include<stdio.h>
#include<malloc.h>
#include<stdlib.h>
#include<conio.h>
#include<ctype.h>
#define Esc 27
#define NULL 0
#define LEN sizeof(struct student)
struct student
{char class_0[20];					//班级int num;							//学号char name[20];						//姓名float c_prog;						//c语言程序设计float eng;							//大学英语float math;							//高等数学float avg;							//平均成绩int order;							//名次struct student *next;
};
int n;									//全局变量，统计学生记录的个数
//函数声明
struct student *create();
void Output(struct student *head);
struct student *Delete(struct student *head, int num);
struct student *insert(struct student *head, struct student *stud);
struct student *Lookup(struct student *head, int num);
struct student *Modify(struct student *head, int num);
float Statistic(struct student *p);
struct student *order(struct student *head);
void start();
void goon();
void exit();
//创建链表，输入学生信息
struct student *create()
{struct student *head;struct student *pl;n=0;pl=(struct student*) malloc(LEN);printf("\n\n\t请输入学生的信息:  \n");printf("\t输入格式为：(每输入一项回车，以学号为0退出!)\n");printf("\t请输入学生学号:");scanf("%d",&pl->num );printf("\t请输入学生姓名:");scanf("%s",&pl->name );printf("\t请输入学生班级:");scanf("%s",&pl->class_0 );printf("\n");printf("\t请输入程序设计成绩:");scanf("%f",&pl->c_prog );printf("\t请输入大学英语成绩:");scanf("%f",&pl->eng );printf("\t请输入高等数学成绩:");scanf("%f",&pl->math );printf("\n");head=NULL;while(pl->num !=0){pl->avg =Statistic(pl);			//求pl的平均值head=insert(head,pl);			//创建链表pl=(struct student*)malloc(LEN);printf("\n\t如果你想结束输入，请输入 0 !\n\n");printf("\t请输入学号:");scanf("%d",&pl->num );if(pl->num ==NULL)				//控制是否退出continue;printf("\t请输入学生姓名:");scanf("%s",&pl->name );printf("\t请输入学生班级:");scanf("%s",&pl->class_0 );printf("\n");printf("\t请输入程序设计成绩:");scanf("%f",&pl->c_prog );printf("\t请输入大学英语成绩:");scanf("%f",&pl->eng );printf("\t请输入高等数学成绩:");scanf("%f",&pl->math );printf("\n");
}return (head);
}
//输出链表
void Output(struct student *head)
{struct student *p;printf("\n\t现在有%d个记录是:\n",n);p=head;printf("\n\n\n****************学生成绩信息表****************\n\n");printf("\n学号\t姓名\t班级\t程序设计  大学英语  高等数学  平均分  学生名次\n");if(head!=NULL)  do{printf("%-10d",p->num );printf("%-10s",p->name );printf("%-8s",p->class_0 );printf("%-8.2f",p->c_prog );printf("\t%-8.2f",p->eng );printf("%-8.2f",p->math );printf("%-8.2f",p->avg );printf("\t%-3d\n",p->order  );p=p->next ;} while(p!=NULL);
}
//根据学号来删除学生信息
struct student *Delete(struct student *head, int num)
{struct student *p1,*p2;if(head==NULL)			//空链表时返回{printf("\n\t链表为空!\n");return(head);}p1=head;while(num!=p1->num &&p1->next!=NULL)					{p2=p1;p1=p1->next ;									}if(num==p1->num )									//链表找到相应的学号{if(p1==head)head=p1->next ;else											//表中和表尾删除p2->next =p1->next ;printf("\n\t你删除的学生信息为: \n");printf("\t学号为：%d\t",p1->num );printf("\t姓名为：%s\t",p1->name );printf("\t班级为：%s\t",p1->class_0 );printf("\n");printf("\t程序设计成绩为：%.2f\t",p1->c_prog );printf("\n");printf("\t\t大学英语成绩为：%.2f\t",p1->eng );printf("\t\t高等数学成绩为：%.2f\t",p1->math );printf("\n");printf("\t\t平均成绩为：%.2f\t",p1->avg );printf("\t学生名次为：%d\t",p1->order );printf("\n");n=n-1;free(p1);}else				//找不到学号printf("\t学号%d没有找到!\n",num);return(head);
}
//插入学生信息
struct student *insert(struct student *head, struct student *stud)
{struct student *p0,*p1,*p2;p1=head;p0=stud;if(head==NULL)				//空链表时返回{head=p0;p0->next =NULL;}else{while((p0->avg <p1->avg   )&&(p1->next  !=NULL)){p2=p1;p1=p1->next;}if(p0->avg >=p1->avg ){if(p1==head)				//链表头插入{p0->next =p1;head->next =p0;}else						//链表中插入{p2->next =p0;p0->next =p1;}}else							//链表尾部插入{p1->next =p0;p0->next =NULL;}}n=n+1;p0->order=0;		//初始化名次return(head);	
}
//根据学生学号来查找学生信息
struct student *Lookup(struct student *head, int num)
{struct student *p1,*p2;p1=head;if(head==NULL)		//空链表时返回{printf("\n\t链表为空！\n");return(head);}else{while(num!=p1->num &&p1->next !=NULL){p2=p1;p1=p1->next ;}if(num==p1->num )							//找到相应的学号则显示{printf("\t你查找的学生信息为：\n");printf("\t学号为：%d\n",p1->num );printf("\t姓名为：%s\n",p1->name );printf("\t班级为：%s\n",p1->class_0 );printf("\t程程序设计成绩为：%.2f\n",p1->c_prog );printf("\t大学英语成绩为：%.2f\n",p1->eng );printf("\t高等数学成绩为：%.2f\n",p1->math );printf("\t平均成绩为：%.2f\n",p1->avg );printf("\t学生名次为：%d\n",p1->order );}else						//	学号不在链表内printf("\t你输入的学号不在链表内！\n");}return(head);
}
//根据学生学号来修改学生的信息
struct student *Modify(struct student *head, int num)
{struct student *p1,*p2;struct student *stude;stude=(struct student*)malloc(LEN);p1=head;if(head==NULL)				//链表为空时不能改变信息{printf("\n\t链表为空！\n");return(head);}else{while(num!=p1->num &&p1->next !=NULL){p2=p1;p1=p1->next;}if(num==p1->num )						//	找到相应的学号时{if(p1==head)						//表头删除head=p1->next ;else								//表中和表尾删除p2->next =p1->next ;printf("\t你要修改的学号为%d的先前信息为：\n",num);printf("\t学号为：%d\n",p1->num );printf("\t姓名为：%s\n",p1->name );printf("\t班级为：%s\n",p1->class_0 );printf("\n");printf("\t程序设计成绩为：%.2f\n",p1->c_prog );printf("\t大学英语成绩为：%.2f\n",p1->eng );printf("\t高等数学成绩为：%.2f\n",p1->math );printf("\t平均成绩为：%.2f\n",p1->avg );printf("\t学生名次为：%d\n",p1->order );printf("\n");printf("\t请输入你要改变的成绩：（格式为：每输入一次回车）\n");printf("\t请输入程序设计成绩：");scanf("%f",&p1->c_prog );printf("\t请输入大学英语成绩：");scanf("%f",&p1->eng );printf("\t请输入高等数学成绩：");scanf("%f",&p1->math );p1->c_prog =stude->c_prog ;p1->eng =stude->eng ;p1->math =stude->math ;p1->avg =Statistic(p1);head=insert(head,p1);n=n-1;}else					//找不到学号时printf("\t你要修改的学号不在链表内！\n");}return(head);
}
//根据学生平均分来排名
struct student *order(struct student *head)
{struct student *p;int i=1;p=head;while(p!=NULL){p->order =i;i++;p=p->next ;}return(head);
}
//根据输入的各科成绩来计算平均分
float Statistic(struct student *p)
{p->avg =(p->c_prog +p->eng +p->math )/3;return p->avg ;
}
void menu()		//系统主界面
{printf("\n\n\t\t	= = =欢迎使用班级成绩管理系统= = =");printf("\n\n\t\t		1.新建学生成绩表	");printf("\n\n\t\t		2.输出学生成绩表		");printf("\n\n\t\t		3.学生成绩排序		   ");printf("\n\n\t\t		4.按学号查找学生成绩信息");printf("\n\n\t\t		5.按姓名修改学生成绩信息  ");printf("\n\n\t\t		6.添加学生成绩信息 ");printf("\n\n\t\t		7.按学号删除学生信息	");printf("\n\n\t\t		ESC.退出系统    ");printf("\n\n\t\t	------------------------------------");printf("\n\n\t\t	  ********请您选择操作选项********	");printf("\n\t\t请输入您的选择(1-7)：");
}
void goon()
{printf("按任意键继续！！！");getch();
}
void exit()
{system("cls");printf("\n\n\n\t\t	= = = = = = = = = = = = = = = = = =");printf("\n\n\t\t	= = =谢谢使用学生成绩管理系统= = =");printf("\n\n\t\t	= = = = = = = = = = = = = = = = = = \n\n");
}
//主函数main()
{struct student *head,*stu;int Delete_num;int lookup_num;int Modify_num;char ckey='a';int istate=0;do{system("cls");				//vc++清屏函数，包含在#include<stdlib.h>中menu();ckey=getch();if(ckey=='1')				//创建{system("cls");head=create();head=order(head);Output(head);istate=1;				//记录链表是否有数据goon();}else if((istate==0)&&(ckey!=Esc)){printf("\n\t错误：你必须先输入学生信息！！！");goon();}else if(ckey=='2')					///显示{system("cls");Output(head);goon();}else if(ckey=='3')					//排序{system("cls");order(head);Output(head);goon();}else if(ckey=='4')					//查找{system("cls");printf("  \n\t请输入你要查找的学生学号：");scanf("%d",&lookup_num);head=Lookup(head,lookup_num);head=order(head);goon();}else if(ckey=='5')				//修改{system("cls");printf("  \n\t请输入你要修改学生信息的学号：");scanf("%d",&Modify_num);head=Modify(head,Modify_num);head=order(head);goon();}else if(ckey=='6')				//插入{system("cls");printf("  \n\t请输入你要插入的学生信息：\n\n");stu=(struct student*)malloc(LEN);printf("\t请输入学生信息，格式为：（每输入一项回车）\n");printf("\t请输入学生学号：");scanf("%d",&stu->num );printf("\t请输入学生姓名：");scanf("%s",&stu->name );printf("\t请输入学生班级：");scanf("%s",&stu->class_0 );printf("\n");printf("\t请输入程序设计成绩：");scanf("%f",&stu->c_prog );printf("\t请输入大学英语成绩：");scanf("%f",&stu->eng );printf("\t请输入高等数学成绩：");scanf("%f",&stu->math );printf("\n");stu->avg=Statistic(stu);				//求stu 的平均值head=insert(head,stu);head=order(head);goon();}else if(ckey=='7')				//删除{system("cls");printf("\n\t请输入你要删除的学生学号");scanf("%d",&Delete_num);head=Delete(head,Delete_num);head=order(head);goon();}}while(ckey!=Esc);				//按键盘上的Esc键退出！！！exit();
}